Were the Dark Ages Triggered by Volcano-Related Climate Changes in 6th C.?

[Dover]

Were the Dark Ages Triggered by Volcano-Related Climate Changes in the 6th Century?
(If so, was Krakatau volcano the culprit?)
by Ken Wohletz
Los Alamos National Laboratory

Modern history has its origins in the tumultuous 6th and 7th centuries. During this period agricultural failures and the emergence of the plague contributed to: (1) the demise of ancient super cities, old Persia, Indonesian civilizations, the Nasca culture of South America, and southern Arabian civilizations; (2) the schism of the Roman Empire with the conception of many nation states and the re-birth of a united China; and (3) the origin and spread of Islam while Arian Christianity disappeared.

In his book, Catastrophe An Investigation into the Origins of the Modern World, author David Keys explores history and archaeology to link all of these human upheavals to climate destabilization brought on by a natural catastrophe, with strong evidence from tree-ring and ice-core data that it occurred in 535 AD. With no supporting evidence for an impact-related event, I worked with Keys to narrow down the possibilities for a volcanic eruption that could affect both hemispheres and bring about several decades of disrupted climate patterns, most notably colder and drier weather in Europe and Asia, where descriptions of months with diminished sun light, persistent cold, and anomalous summer snow falls are recorded in 6th-century written accounts.

Writings from China and Indonesia describe rare atmospheric phenomena that possibly point to a volcano in the Indonesian arc. Although radiocarbon dating of eruptions in that part of the world are spotty, there is strong bathymetric and volcanic evidence that Krakatau might have experienced a huge caldera eruption. Accordingly, I encouraged a scientific expedition to be led by Haraldur Sigurdsson to the area. The expedition found a thick pyroclastic deposit, bracketed by appropriate radiometric dates, that suggests such a caldera collapse of a “Proto-Krakatau” did occur perhaps in the 6th century. Bathymetry indicates a caldera some 40 to 60 km in diameter that, with collapse below sea level, could have formed the Sunda Straits, separating Java from Sumatra, as suggested by ancient Javanese historical writings. Such a caldera collapse likely involved eruption of several hundred cubic kilometers of pyroclastic debris, several times larger than the 1815 eruption of Tambora...cont'd

http://www.ees1.lanl.gov/Wohletz/Krakatau.htm

[aquart]

1. saw it on PBS. Nova?

[sam sarrha]

2. wasnt it the erutpion of toba near sumatra, 350mi from the last tsumani

that caused the last ice age..

[tocqueville]

3. the recent Dark Ages were triggered by a GOP vulcano in Washington.... nt

[Dead_Parrot]

4. Overstating it, I think.

The main cause of the European Dark ages was the collapse of the Roman Empire: Pax Romana had died in the 3rd Century, and in the 4th Rome was subject to almost endless civil conflict, invasions and the territorial schisms. The dark ages were well underway for most of Europe by the time the Western empire finally called it a day in 476 - well before this eruption.

Sounds like a good bit of geological detective work, though.

[happyslug]

6. Agreed, PAX ROMANA ended about 250 AD.

When the Sassanids in 227 AD, overthrow the previous Parthian rulers of Persia (This revolt stems form the earlier Invasion and sacking of the Parthian Capital by Septimius Severus in 198 AD) Rome, for the first time since the Destruction of Carthage, had an enemy almost as powerful as itself. Under Parthian Rule, Persia had been a minor problem (To far from the Mediterranean for Rome to Conquer and hold but close enough for Rome have to worry about). Under the Sassanids, Persia was no longer a weak Feudal Government but a strong Centralized Government as powerful as Rome in the Persian Gulf, the Indus Valley and right in Now Iraq. Previously Rome could always invade Persia any time Rome wanted and take the Persian Capital (As Severus had done in 198 AD) afterward no Roman Leader would take Persia till Heraclius (610 - 641 A.D.). Trajan had done so in 98 AD, but Hadrian withdrew the Roman Forces as being over extended. From 227 onward, Rome had a formidable on its Eastern Frontier.

As to the Danube Frontier, the Goths seems to have moved into Right is now the Hungary Plain And extended their control to right is now the Ukraine. This permitted the Goths to launch both land and sea attacks on the Empire from across the Danube and the Black Sea. At the same time Rome was having a hard time finding the money needed to pay its troops (and the larger armies needed given the new threats on the Frontiers).

Against these dual threats Rome Prevailed, but because the People of the Empire wanted to stay in the Empire. This is a remarkable change in altitude, if the above had occurred 200 years before Rome would have had widespread revolts, instead it had some problems on the Frontiers, some invasions, two revolts which were more efforts to replace the ruling Emperors than to free themselves from Roman Rule. These facts plus the larger army raised saved the Empire, but it was clear it was no longer an Empire, but a unified Country. This unity was further enhanced by the widespread adoption of Christianity provided a Empire wide Religion (and this is BEFORE Constantine made Christianity the "official" Religion of the Empire.

The problems for the Empire in the 300s was less external than internal, how do you raise a large army? During the Days of the Roman Republic The republic had required military service of ALL of its citizens. As the Republic became an Empire this requirement fell on the wayside, for people who fight for a Country want a voice in the Ruling of that Country. The Roman ruling elite did NOT want the Roman Peasants to have that right so converted to a mercenary army (about 90 BC) rather than give RIGHTS to the peasants.

With the Destruction of Carthage (146 BC) and the subsequent destruction of what was left of the Successor of Alexander's Empire, Rome no longer needed a large army, no one could challenge its power. Rome could afford to have a small mercenary Army, which it did from the Days of Augustus to the late 200s (It is believe during this period Rome had only 30 legions, roughly 90,000 men under arms from England to Egypt, during the time of Caesar Rome had had at least 67 legions PLUS foreign Troops but that was the HEIGHT of Size of the Roman Mercenary Army).

Thus Rome from the late 200s needed a larger Army then it had needed for 200 years. Rome expanded its existing Mercenary Army, but this cost a huge financial burden which lead to economic decline. The solution to the Economic Decline was to cut taxes (Especially on the poor) but to do so would mean cutting back the pay of the Soldiers. Modern Armies solved this problem the same way the Roman Republic had, by adopting some sort of Universal Military Service, but the Roman Elite did not want this then the peasants would be able to revolt SUCCESSFULLY or worse just DEMAND fair treatment in the matter of Taxation (The Emperor Heraclius, 610 to 641 A.D., would adopt this policy, by giving land to his men but that is AFTER the fall of the Empire in the West AND even the Fall of Egypt to, at first the Persians, and then the Arabs. Thus the old ruling elite who owned most of the land in Egypt and Western Europe were no longer a factor in the Empire).

Thus from the late 200s to the early 600s Rome had a problem, raising an army WITHOUT providing military training to the Roman Peasants. Rome at first Raised Taxes, then destroyed the old Temples (More for the Gold in the Temples than to end paganism), then hired foreign mercenaries, and only when all these other evils had been tried first and shown to be the evils their were did the Roman Ruling Elite armed their owned peasants. This arming of the Roman Peasants (The Empire had been reduced by that time to right is now Greece and Turkey) stabilized the Empire for almost 400 years (In fact during the 900s the Empire was planning to launch at least two invasions of Egypt and Palestine to re-gain these areas but to the Empire, but the deaths of the Emperors involved ended both invasion plans). It is only with the invasion by the Seljuk Turks after 1000 that the Empire suffered further decline and this appears to be only minor until the Fourth Crusade destroyed the Empire when it took Constantinople in 1204 AD (and this appears to reflect the increase strength of Western Europe in the High Middle ages then any decline in what the People of Constantinople still called at that time the Roman Republic).

As to the fall of the Empire in the West, while 476 AD is considered the "Fall of the Western Roman Empire", that is not quite true. Since 450 AD the Western Emperor had been a puppet of his German Mercenaries, but the Roman State in the west continued and continued through the Rule of the Goths and the Conquest of Italy by Roman Forces in the 520-540s. The real shift in Attitude occurred after the Lombard Invasion of 570 AD, Italy north of Rome (except for Venice) never again became part of the Empire, Rome itself would stay loyal to the Empire, but its real ruler became the Popes (more by default than any desire of the popes from Gregory the Great onward to rule). This independence of the Rome from the Empire increased with the Arab Invasions of the 600s leading to de factor independence of Rome From the Empire by 700 AD (Some one had to handle the affects of the Arab Invasion with the Empire concentrated on Southern Italy and Turkey ignoring Arab raids into Spain, Northern Italy and Southern France).

Thus the better way to view the Fall of the Empire is do to an inability of the Roman Empire to want to "empower" its peasants. When the Peasants were "empowered" Under Heraclius (610 - A.D.) or under the Lombards (570 onward) the decline STOPPED. The problem was such "Empowerment" would lead to land reform which the Roman land owners did NOT want. The lack of land reform would delay Western Europe get back on its feet till after 900 AD when Feudalism was adopted first in Northern Germany and then the rest of Europe. One of the affects of Feudalism was Peasants were empowered by giving them Rights to their Lands (not 100% ownership rights but Rights that their lord had to respect and honor). With Feudalism Western Europe was able to regain the strength in had under the Early Empire and slowly become the power Western Europe is today.

My point was if a Volcano went up about 500 AD, it was just additional icing on the cake (and occurred during the Reconquest of Italy by Roman Forces as opposed to a period of Decline of the Empire). The volcano may have had an affect but what given its late date (early sixth century i.e 500-530 AD)? It is to late for what happened prior to the Reconquest of Italy, and it is to early for the Lombard Invasion of 570 AD. Could it have driven the Slavic Invasions of the 600s? (These reached as far as the Elbe in Germany and deep into Greece, a problem the Empire, now generally called the Byzantine Empire, had to deal with at the same time as the Arab Conquest)? For these invasion the volcano is to early, over 100 years to early. Could the Volcano have force the movement of people to END (Thus permitting China to re-Unite AND Rome to almost reunite under Justinian)? More questions than answers given the time period of the eruption AS CITED IN THE ARTICLE.

[Odin2005]

7. Excelent post.

IMO, this recent trend of emphasizing enviromental causes of the collpase of civilizations smacks of a passing fad. It reminds me of how Victorian Age moralists tried to blame the fall of Rome on moral degeneracy.

[phantom power]

8. On Ye Other Hand...

This fad captures an important core of truth. All civilizations are profoundly intertwined with environment and climate. Proximity to resources, availability of reliable food supply, public health, etc.

If the fad recedes, I hope it leaves behind an increased awareness of the fact that any civilization can take a mortal blow from environmental disaster, and that such a blow can be self-inflicted.

[happyslug]

10. The old rule of History was great times brings forth Great leaders.

And ordinary times brings forth idiots (When this rule is violated as to "Great times" you see the total collapse of countries, dynasties, Civilizations, ruling elites etc). Thus the worse time of Roman dependency was during the time of its height when Rome was the unchallenged master of the world. At such times the degenerate ruling elite could cause no more harm to Rome then they were doing based on they suppression of the poor. When Rome was in decline, Rome could no longer afford such degeneracy and reverted to a more "Normal" level of social behavior. People will tolerate degenerate rulers when they can cause no harm (or are competent but Competency is often tied in with an ability to rule which most perverts just do not have the time for, their perversions take precedent). Rulers are NOT overthrown do to degeneracy but degeneracy is often used as the excuse to overthrow incompetent Rulers especially when the incompetency is causing harm to the Nation.

Rome had been in decline since the time of Marius (who had first "Reformed" the Roman into a Mercenary Army in 90 BC). The reason for this "Reform" was the interests of the Roman Poor and Roman ruling elite had diverged since the Second Punic War (about 200BC). Prior to the reform Rome needed its poor to man its legions, after the reform the rulers of Rome only needed Money. Thus the Roman Elite no longer had to provide something for the poor and thus the diverges between the Roman poor and Roman ruling elite diverged more and more. Thus after 90 BC the Roman Ruling Elite no longer trusted its poor to protect the interests of the Nation (or more accurately the best interests of the poor Romans were NOT the same as the best interests of the Roman elite). The Roman poor refused to fight for what the Roman Elite called "Rome". Caesar and Augustus would still use the poor Romans to back they plans for Rome, but till the mid 200s you had no Roman leader who really considered that the Poor Romans wanted (In between the Roman Emperors would do things for the Poor, in the name of the poor, but NOT give any power to the Roman poor till the near fall of the Empire in the mid-200s). Afterward Rome could no longer afford to have its Rulers be as degenerated as the Roman Rulers in the first Century AD and the history or Rome reflected that need (This was one of the reasons Rome Adopted Christianity at that time period, Christianity united both the rich and poor into one "People" Something Rome had not been since the Death of Augustus in 14 AD).

Look up the "Roman Revolution" for the details on the change in Roman history between 90 and 44 BC. The change is great, but it is the reflection of the lost of power of the Roman Poor do to the adoption of an Mercenary Army to replace the Militia type army of the earlier Republic. Similarly until Rome readopted a militia type army around 620 AD, Rome suffered decline both internally and in size (Which also meant foreign Conquest to take over other lands was no longer possible for the Militia would only fight to defend "Rome" as their defined "Rome" not as the Ruling elites defined "Rome"). You had Byzantine Armies in the Ukraine, but NOT to Conquer the Ukraine, You had the Invasion of Persia, but to defend "Rome" not to conquer Persia. As to Egypt, the Eastern Empire had been divided equally between the "Arab" Speaking countries of Egypt and Syria and the Greek Speaking Countries of Greece and Asia Minor. When the Arabs took Egypt, Rome tried to re-take it the next year, but as long the the Citizens of Egypt no longer wanted to be ruled from Greek Constantinople, the new Militia Army was NOT going to stay to fight for a Country that did not want to stay "Roman". Thus the Roman army was driven out the same year do more to lack of local support than the actual effort of the Arabs (Who were few in Numbers compared to the then Christan Population of Egypt).

This is the hazard of a militia Army, you can NOT send it without the support of the "people" (For the Militia and people are one and the same). Rome after 600 AD could no longer afford a purely mercenary army and thus the people regain much of their power they had during the Roman Republic. It took almost 700 years to re-gain that power, but they did do to the dangers to the Country that even the Ruling elite finally accepted that arming the poor was better than hiring foreign Mercenaries.

Back on track, what about the 500s? This was the period of ROMAN EXPANSION (back into Italy, North Africa and Spain, but it was expansion from what the Roman Empire was in 500 AD). The large movement of the "Barbarians" were of the previous century (and would resume in the next century) but what caused them to STOP in the 500s? And resume later on? Could it be that the Volcano made things so harsh that no one wanted to move.

There is a observations in history that as things go down hill you do NOT have revolutions, Revolutions occur only after things have bottomed out and the economy is IMPROVING.Thus the worse year for France was 1787, and you had revolution in 1789 as things started to improve. You had the Russia Revolution in 1917 when the Russia Front worse year for WWI had been in 1916. The same may be in the 500s, the Volcano may have made things WORSE and until the climate effect had worked it way through the system you had no movement of people no revolutions. Thus if the Volcano went off in 530 or about, the whole world economy could have gone downhill forcing people to be concern about they next meal as opposed to who to loot (I am talking about the "Barbarians" here). Thus Rome was no longer facing any movement of tribes and thus had excess resources to use to retake Italy (The same with China, no movement of the "Barbarian" Tribes do to hard times among the tribes so China has a window of opportunity to re-unite). This window closed as the affect of the Volcano receded and the Tribes once again had excess resources to launch large scale attacks on Roman Territory (and may even explain the Persian willingness NOT to attack Rome in the early years of the War to re-take Italy but as the effect of the Volcano receded Persia had more and more resources to use to attack Roman Territories along its border, thus forcing Rome to re-man its Eastern Defenses ending the reconquest of the Western Roman Empire).

The resumption of the threat of the "Barbarian" Tribes also restarted the decline in Roman Economy that would lead to the reforms of the 600s as what remains of the Roman State became a Greek State in order to save what was left of the Roman Republic (The official name of the Roman State till 1453 when Constantinople fell to the Turks).

[Dead_Parrot]

9. We like to have clear-cut reasons for things

It's like the mammoth-extinction thread we've just had: We like to be able to say "X caused Y" and leave it at that, when of course the whole thing is linked to a mind-bogglingly complex interplay of circumstances.

In a few cases, it works nicely: We can point to the end of the Minoan civilisation, and the fucking big hole in Santorini, and say "Aha!": But when you've got something as complex as fall of Rome (where, as Happyslug shows, it's tricky even to pin "it" down to within a century) things are a little more involved.

I think the fad has been caused by the realisation that enviroment does affect culture, so everyone's been playing boy detective and finding links between natural and human events. But instead of just saying "this might be another factor", we've wound up with "this is the real cause".

Look up the works of Immanuel Velikovsky to take that to it's surreal conclusion...

[Odin2005]

5. I wouldn't say it CAUSED the Dark Ages, at least in Western Europe.

Barbarians had already overrun the western part of the Roman Empire and the whole of Graceo-Roman society had been rotting since the 2nd century BC durinng Rome's 2nd war with Carthage. The cooling caused by the eruption may have been what allowed the massive plauge that caused a massive amount of depopulation. East Roman Emperor Justinian's attempt of regaining Northern Italy also lead to Italy to be utterly devastated (coincidentally, Justinian launched his war against the Goths in Italy the same year the eruption occured, 535!). The Dark Age eastern Mediterranean is not given the importance it deserves in discussions of the disintergration of the Roman Empire, it is the Slavs and the Arabs that finaly gave the Greaco-Roman civilization it's coupe de grace.

http://en.wikipedia.org/wiki/Byzantine_Empire

The reign of Justinian I, which began in 527, saw a period of extensive imperial conquests of former Roman territories (indicated in green on the map below). The 6th century also saw the beginning of a long series of conflicts with the Byzantine Empire's traditional early enemies, such as the Sassanid Persians, Slavs and Bulgars. Theological crises, such as the question of Monophysitism, also dominated the empire.

Justinian I had perhaps already exerted effective control during the reign of his predecessor, Justin I (518–527). Justin I was a former officer in the imperial army who had been chief of the guards to Anastasius I, and had been proclaimed emperor (when almost 70) after Anastasius' death. Justinian was the son of a peasant from Illyricum, but was also a nephew of Justin. Justinian was later adopted as Justin's son. Justinian would become one of the most refined people of his century, inspired by the dream to re-establish Roman rule over all the Mediterranean world. He reformed the administration and the law, and with the help of brilliant generals such as Belisarius and Narses, he temporarily regained some of the lost Roman provinces in the west, conquering much of Italy, North Africa, and a small area in southern Spain.

In 532, Justinian secured for the Eastern Roman Empire peace on the eastern frontier by signing an "eternal peace" treaty with the Sassanid Persian king Khosrau I. However, this required in exchange a payment of a huge annual tribute of gold. The same year, the Nika riots, or Nika revolt, lasted for one week in Constantinople. It was the most violence the polis had ever seen to that point and nearly half of it was burned or destroyed.

Justinian's conquests in the west began in 533 when Belisarius was sent to reclaim the former province of North Africa with a small army of 18,000 men who were mainly mercenaries. Whereas an earlier expedition in 468 had been a failure, this new venture was successful. The kingdom of the Vandals at Carthage lacked the strength of former times under King Gaiseric and the Vandals surrendered after few battles against Belisarius' forces. General Belisarius returned to a Roman triumph in Constantinople with the last Vandal king, Gelimer, as his prisoner. However, the reconquest of North Africa would take a few more years to stabilize. It was not until 548 that the main local independent tribes were entirely subdued.

In 535, Justinian I launched his most ambitious campaign, the reconquest of Italy. At the time, Italy was still ruled by the Ostrogoths. He dispatched an army to march overland from Dalmatia while the main contingent, transported on ships and again under the command of General Belisarius, disembarked in Sicily and conquered the island without much difficulty. The marches on the Italian mainland were initially victorious and the major cities, including Naples, Rome and the capital Ravenna, fell one after the other. The Goths were seemingly defeated and Belisarius was recalled to Constantinople in 541 by Justinian. Belisarius brought with him to Constantinople the Ostrogoth king Witiges as a prisoner in chains. However, the Ostrogoths and their supporters were soon reunited under the energetic command of Totila. The ensuing Gothic Wars were an exhausting series of sieges, battles and retreats which consumed almost all the Byzantine and Italian fiscal resources, impoverishing much of the countryside. Belisarius was recalled by Justinian, who had lost trust in his preferred commander. At a certain point, the Byzantines seemed to be on the verge of losing all the possessions they had gained. After having neglected to provide sufficient financial and logistical support to the desperate troops under Belisarius' former command, in the summer of 552 Justinian gathered a massive army of 35,000 men (mostly Asian and Germanic mercenaries) to contribute to the war effort. The astute and diplomatic eunuch Narses was chosen for the command. Totila was crushed and killed at the Busta Gallorum. Totila's successor, Teias, was likewise defeated at the Battle of Mons Lactarius (central Italy, October 552). Despite continuing resistance from a few Goth garrisons, and two subsequent invasions by the Franks and Alamanni, the war for the reconquest of the Italian peninsula came to an end.

Justinian's program of conquest was further extended in 554 when a Byzantine army managed to seize a small part of Spain from the Visigoths. All the main Mediterranean islands were also now under Byzantine control. Aside from these conquests, Justinian updated the ancient Roman legal code in the new Corpus Juris Civilis. Even though the laws were still written in Latin, the language itself was becoming archaic and poorly understood even by those who wrote the new code. Under Justinian's reign, the Church of Hagia Sofia ("Holy Wisdom") was constructed in the 530s. This church would become the center of Byzantine religious life and the center of the Eastern Orthodox form of Christianity. The 6th century was also a time of flourishing culture and even though Justinian closed the university at Athens, the Eastern Roman Empire produced notable people such as the epic poet Nonnus, the lyric poet Paul the Silentiary, the historian Procopius, the natural philosopher John Philoponos and others.

The conquests in the west meant that the other parts of the Eastern Roman Empire were left almost unguarded even though Justinian was a great builder of fortifications in Byzantine territories throughout his reign. Khosrau I of Persia had, as early as 540, broken the pact previously signed with Justinian and plundered Antiochia. The only way Justinian could forestall him was to increase the sum he paid to Khosrau I every year. The Balkans were subjected to repeated incursions where Slavs had first crossed the imperial frontiers during the reign of Justin I. The Slavs took advantage of the sparsely-deployed Byzantine troops and pressed on as far as the Gulf of Corinth. The Kutrigur Bulgars had also attacked in 540. The Slavs invaded Thrace in 545 and in 548 assaulted Dyrrachium, an important port on the Adriatic Sea. In 550, the Sclaveni pushed on as far to reach within 65 kilometers of Constantinople itself. In 559, the Eastern Roman Empire found itself unable to repel a great invasion of Kutrigurs and Sclaveni. Divided in three columns, the invaders reached Thermopylae, the Gallipoli peninsula and the suburbs of Constantinople. The Slavs feared the intact power of the Danube Roman fleet and of the Utigurs (paid by the Romans themselves) more than the resistance of the ill-prepared Byzantine imperial army. This time the Eastern Roman Empire was safe, but in the following years the Roman suzerainty in the Balkans was to be almost totally overwhelmed.

Soon after the death of Justinian in 565, the Germanic Lombards, a former imperial foederati tribe, invaded and conquered much of Italy. The Visigoths conquered Cordoba, the main Byzantine city in Spain, first in 572 and then definitively in 584. The last Byzantine strongholds in Spain were swept away twenty years later. The Turks emerged in Crimea, and in 577, a horde of some 100,000 Slavs had invaded Thrace and Illyricum. Sirmium, the most important Roman city on the Danube, was lost in 582, but the Eastern Roman Empire managed to maintain control of the river for several more years even though it increasingly lost control of the inner provinces.

Justinian's successor, Justin II, refused to pay the tribute to the Sassanid Empire. This resulted in a long and harsh war which lasted until the reign of his successors Tiberius II and Maurice, and focused on the control over Armenia. Fortunately for the Byzantines, a civil war broke out in the Persian Empire. Maurice was able to take advantage of his friendship with the new king Khosrau II (whose disputed accession to the Persian throne had been assisted by Maurice) in order to sign a favorable peace treaty in 591. This treaty gave the Eastern Roman Empire control over much of western Armenia. Maurice reorganized the remaining Byzantine possessions in the west into two Exarchates, the Ravenna and the Carthage. Maurice increased the Exarchates' self-defense capabilities and delegated them to civil authorities.

The Avars and later the Bulgars overwhelmed much of the Balkans, and in the early 7th century the Sassanids invaded and conquered Egypt, Palestine, Syria and Armenia. The Persians were eventually defeated and the territories were recovered by Emperor Heraclius in 627. However, the unexpected appearance of the newly-converted and united Muslim Arabs took the territories by surprise from an empire exhausted from fighting against Persia, and the southern provinces were overrun. The Eastern Roman Empire's most catastrophic defeat of this period was the Battle of Yarmuk, fought in Syria. Heraclius and the military governors of Syria were slow to respond to the new threat, and Byzantine Mesopotamia, Syria, Egypt, and the Exarchate of Africa were permanently incorporated into the Muslim Empire in the 7th century, a process which was completed with the fall of Carthage to the Caliphate in 698.

The Lombards continued to expand in northern Italy, taking Liguria in 640 and conquering most of the Exarchate of Ravenna in 751, leaving the Byzantines with control of only small areas around the toe and heel of Italy, plus some semi-independent coastal cities like Venice, Naples, Amalfi and Gaeta.

The Eastern Roman Empire's loss of territory was offset to a degree by consolidation and an increased uniformity of rule. Emperor Heraclius fully Hellenized the Eastern Roman Empire by making Greek the official language, thus ending the last remnants of Latin and ancient Roman tradition within the empire. The use of Latin in government records, (Latin titles such as Augustus and the concept of the Eastern Roman Empire being one with Rome) fell into abeyance, which allowed the empire to pursue its own identity. Many historians mark the sweeping reforms made during the reign of Heraclius as the breaking-point with Byzantium's ancient Roman past. It is common to refer to the Eastern Roman Empire as "Byzantine" instead of as "East Roman" from this point onwards. Religious rites and religious expression within the empire were now also noticeably different from the practices upheld in the former imperial lands of western Europe. Within the empire, the southern Byzantine provinces differed significantly in culture and practice from those in the north, observing Monophysite Christianity rather than Chalcedonian Orthodox. The loss of the southern territories to the Arabs further strengthened Orthodox practices in the remaining provinces.

http://en.wikipedia.org/wiki/Early_Middle_Ages#Migration_Period

As the authority of the Western Roman Empire dwindled in Western Europe, its territories were entered and settled by succeeding waves of "barbarian" tribal confederations, some of whom distrusted and rejected the classical culture of Rome, while others, like the Goths admired it and considered themselves the legatees and heirs of Rome. Prominent among these peoples in the movement were the Huns and Avars and Magyars with the large number of Germanic and later Slavic peoples.

The era of the migrations is referred to as the Migration Period. It has historically been termed the "Dark Ages" by Western European historians, and as Völkerwanderung ("wandering of the peoples") by German historians. The term "Dark Ages" has now fallen from favour, partly to avoid the entrenched stereotypes associated with the phrase, but also partly because more recent research into the period has in fact revealed its surprising artistic sophistication, though its political and social senses were unevolved and its technologies undeveloped, compared to the preceding culture.

Although the settled population of the Roman period were not everywhere decimated, the new peoples greatly altered established society, and with it, law, culture and religion, and patterns of property ownership. The Pax Romana, with its accompanying benefits of safe conditions for trade and manufacture, and a unified cultural and educational milieu of far-ranging connections, had already been in decline for some time as the 5th century drew to a close. Now it was largely lost, to be replaced by the rule of local potentates, and the gradual break-down of economic and social linkages and infrastructure.

This break-down was often fast and dramatic as it became unsafe to travel or carry goods over any distance and there was a consequent collapse in trade and manufacture for export. Major industries that depended on trade, such as large-scale pottery manufacture, vanished almost overnight in places like Britain. The Islamic invasions of the 7th and 8th centuries, which conquered the Levant, North Africa, Spain, Portugal and some of the Mediterranean islands (including Sicily), increased localization by halting much of what remained of seaborne commerce. So where sites like Tintagel in Cornwall had managed to obtain supplies of Mediterranean luxury goods well into the 6th century, this connection too was lost. Administrative, educational and military infrastructure quickly vanished, leading to the rise of illiteracy among leadership.