Late antiquity: Diocletian to the Arab conquests

Detail

What 'late antiquity' means

• 'Late antiquity' is the name given to the last phase of the Roman empire — roughly the fourth to the seventh centuries CE.
• It is not simply a story of decline. It is a period of change and break-up: new religion, new capital, new army structure, new kingdoms in the West.
• Two things happen side by side: the West breaks into many kingdoms, and the East stays one rich state.

Diocletian (284–305): shrinking to survive

• Diocletian saw that the empire had grown too big to defend. So he did the opposite of conquest.
• Gave up territories that had little strategic or economic value — land that cost more to hold than it gave back.
• Fortified the frontiers — built up forts and defence lines along the borders.
• Redrew provincial boundaries — by 297 the empire had about 100 provinces, each smaller, so governors could control them better.
• Separated civilian work from military work. Earlier one governor did both. Now:
• civil officials handled tax and justice,

• military commanders called duces (singular dux) handled troops, with real freedom of action in their own zone.

• He also divided rule at the top into a tetrarchy — a college of four rulers: two senior emperors (Augusti) and two junior emperors (Caesares). Diocletian and Maximian (Augustus from 286) were the seniors; Constantius and Galerius became Caesars in 293. All four were tied by adoption or marriage, and all were Illyrians who rose through long army careers [2].

• He ruled for over 20 years (284–305) and his reform of tax, administration and army became the base on which the later Byzantine state in the East was built [2].

Constantine: new religion, new coin, new capital

• Christianity became the official religion under Constantine. His own conversion is dated 312.
• Monetary innovation: he introduced the solidus, a gold coin, around c. 310. It was reliable in weight, so it stayed in use for centuries and made long-distance trade easier.
• Second capital at Constantinople, founded 324. The site was the old Greek city of Byzantium. It had sea on three sides, which made it very hard to attack. Constantine gave it its own senate, so it was a real capital, not a second-rank city.

The fourth-century boom — the East was not poor

• The fourth century brought stable money, a growing governing class (more officials, more jobs, more spending), and a real economic revival.
• Money went into production equipment, not just luxury:
• oil presses and screw presses (a screw turned to squeeze more oil or wine out of the same fruit),
• glass factories,

• multiple water-mills (several mills fed by one water channel, so grain was ground faster).

• Long-distance eastern trade revived — goods again moved between the Mediterranean, the Red Sea and further east.

• Tax figures show the scale. Egypt under Justinian paid over 2.5 million solidi a year — about 35,000 lbs of gold, from one province alone.
• Parts of the Near Eastern countryside were more developed and more densely settled in the fifth–sixth centuries than in the twentieth century. Archaeological surveys of villages show this. So "late" does not mean "declining" everywhere.

Religion before and during Christianisation

• Classical Roman religion was polytheist — many gods worshipped together.
• The chief Roman gods: Jupiter, Juno, Minerva, Mars.

• Plus countless Greek and eastern deities absorbed into Roman worship.

• Important point for answers: polytheists had no common name for themselves. They did not think of themselves as one religion. Only Christians and Jews had a clear single label.

• Judaism was also not a monolith — Jewish communities differed a lot in practice and belief between regions.
• Christianisation was gradual and complex:
• Polytheism did not vanish overnight — temples, festivals and old habits continued.
• In the fourth century religious boundaries were fluid — people moved between practices, or mixed them.

• Boundaries hardened later, as bishops disciplined their laity (the ordinary church members, as opposed to priests) and told them what a Christian may and may not do.

• Violence came with the change: the Serapeum at Alexandria, a great temple of the god Serapis, was destroyed in 391.

West: political break-up into 'post-Roman' kingdoms

• The West fragmented politically. Germanic groups settled inside the empire and carved out their own states — historians call these 'post-Roman' kingdoms. They are the seed of medieval Europe.
• Key kingdoms:
• Visigoths in Spain — destroyed by the Arabs, 711–20.
• Franks in Gaul — roughly c. 511–687.
• Lombards in Italy — 568–774.
• Ostrogothic kingdom in Italy from 493.

• Vandals took Africa in 428.

• Military shocks on the way:

• 378 — Goths crush Roman armies at Adrianople. A Roman field army destroyed and an emperor killed.
• 410 — Visigoths sack Rome. A huge psychological blow, though Rome was no longer the working capital.

• 434–53 — empire of Attila, the Hun ruler, pressing on both halves.

• Note the wording carefully for exams: the West fragmented politically, it was not simply "destroyed". Cities, bishops, Latin and Roman law continued inside these kingdoms.

East: united, prosperous, and at its peak under Justinian

• The East remained united and prosperous. Its population kept growing into the sixth century, even after the plague of the 540s.
• Justinian (527–65) is the high-water mark of the eastern empire.
• Africa recovered from the Vandals in 533.

• But the recovery of Italy devastated the peninsula — the long war wrecked the country and opened the way to the Lombards (who arrived 568).

• Justinian's other legacies (external detail, extending the scaffold):

• The Corpus Juris Civilis ('Body of Civil Law'), issued 529–534, in four parts: Codex Constitutionum, Digesta (Pandectae), Institutiones and Novellae. The Codex was promulgated in 529, the Institutiones (a textbook for first-year law students, supervised by Tribonian) in 533, and a revised Codex Repetitae Praelectionis in 12 books in 534. It is the base of the modern civil law tradition [3][4].
• The Nika riots of 532 in Constantinople: the chariot-racing factions, the Blues and the Greens, joined together against Justinian. He survived, and came out stronger [5].
• Hagia Sophia, built 532–537 by the architects Anthemius of Tralles and Isidorus of Miletus, with a huge main dome rebuilt in 563 resting on pendentives (curved triangles that carry a round dome on a square base) [6].

Rome versus Iran — the final act

• Rome and the Sasanian empire of Iran had fought for centuries. The last round nearly killed both.
• Khusro II invaded the eastern provinces, including Egypt, in 614–19. Syria, Palestine and Egypt — the richest tax lands — were lost.
• Byzantium recovered them in the 620s under Heraclius.
• The timing matters: recovery came only a few years before the blow from the south-east. Both empires were exhausted, with drained treasuries and worn-out armies, exactly when the Arabs came.

Islam and the Arab conquests

• The rise of Islam is called the greatest political revolution ever to occur in the history of the ancient world.
• Speed is the striking fact. By 642, barely ten years after the Prophet's death, large parts of both the eastern Roman and the Sasanian empires had fallen to the Arabs.
• Within a century the conquests reached Spain, Sind and Central Asia — three continents again, but under a new power.
• The key factor was not Roman weakness alone. It was the emerging Islamic state's prior unification of the Arab tribes of the peninsula. Tribes that once fought each other now fought together, under one authority, with one purpose.
• Battles that decided it (external detail):
• Battle of Yarmouk, begun 20 August 636 and fought over six days near the border of present-day Syria and Jordan. Arab forces under Khalid ibn al-Walid destroyed the Byzantine army of Heraclius in the ravines of the Yarmuk valley; Christian Arab, Armenian and other auxiliaries deserted the Byzantine side [7].

• Battle of al-Qadisiyyah (636/637), fought near al-Hirah in present-day Iraq, ended the Sasanian army of Yazdegerd III and began Arab and Islamic rule in Persia [8].

• Further anchors: 622 — hijra; 661–750 — Umayyads; 698 — Arabs take Carthage; 711 — Arab invasion of Spain.

Timeline anchors for this section

• 66–70 — Jewish revolt; capture of Jerusalem.
• 212 — all free inhabitants of the empire made Roman citizens.
• 273 — Palmyra destroyed.
• 284–305 — Diocletian.
• 297 — Diocletian's 100 provinces.
• c. 310 — solidus. 312 — Constantine's conversion. 324 — Constantinople founded.
• 378 — Adrianople. 391 — Serapeum destroyed. 410 — sack of Rome. 428 — Vandals take Africa.
• 434–53 — Attila. 493 — Ostrogothic Italy. 527–65 — Justinian. 533 — Africa recovered. 540s — plague. 568–774 — Lombards.
• 614–19 — Khusro II's invasion. 620s — Byzantine recovery. 622 — hijra. 642 — both empires largely overrun.
• 661–750 — Umayyads. 698 — Carthage. 711 — Spain invaded; Visigoths finished by 720.

Prelims Hooks

• Diocletian's military commanders with autonomy after civil and military functions were split were called duces.
• Solidus, the stable gold coin of late antiquity, was introduced by Constantine around c. 310.
• Constantinople was founded in 324 on the site of the old city of Byzantium, had sea on three sides, and was given its own senate.
• Egypt under Justinian paid taxes of over 2.5 million solidi a year, about 35,000 lbs of gold.
• 212 CE — all free inhabitants of the empire were made Roman citizens.
• 378 CE — Adrianople, where the Goths crushed Roman armies; 410 CE — the Visigoths sacked Rome.
• Justinian (527–65) recovered Africa from the Vandals in 533; his Corpus Juris Civilis was issued 529–534, the revised Codex of 534 having 12 books [3][4].
• Hagia Sophia was built 532–537 by Anthemius of Tralles and Isidorus of Miletus; its main dome was rebuilt in 563 [6].
• Khusro II of Iran held the eastern provinces including Egypt in 614–19; Byzantium took them back in the 620s.
• Battle of Yarmouk began 20 August 636, led by Khalid ibn al-Walid against Heraclius; al-Qadisiyyah (636/637) ended the Sasanians under Yazdegerd III [7][8].
• Post-Roman kingdoms: Visigoths in Spain, Franks in Gaul (c. 511–687), Lombards in Italy (568–774).

Mains Points

• Late antiquity is transformation, not simple "fall". The West lost political unity to post-Roman kingdoms, but the East kept one state, growing population and heavy tax yields into the sixth century. Any answer that says "the Roman empire fell in 476" ignores half the empire and three more centuries of it.
• Diocletian shows that retreat can be strategy. Abandoning low-value land, fortifying frontiers, splitting 100 smaller provinces and separating civil from military command traded reach for control. Useful comparison with any state that overextends and then consolidates — and the same split later let military commanders grow strong.
• Religious change was slow and negotiated, not a switch. Polytheists had no single self-label, Judaism was diverse, and fourth-century boundaries were fluid until bishops disciplined the laity. Good material for questions on how new religions spread inside old states — through institutions and discipline, not one royal conversion.
• The Arab conquests were won by unity, not only by enemy weakness. Rome and Iran had just wrecked each other (614–19, then the 620s recovery, plague of the 540s). But the decisive factor was the Islamic state's unification of the Arab tribes — organisation on the winning side, exhaustion on the losing side. This is also the hinge point where the ancient Mediterranean world ends and the medieval world begins.