The Ostrogothic Kingdom ruled Italy from 493 to 553, preserving Roman administration under Gothic kings until Justinian's armies destroyed it.
The Ostrogothic Kingdom held Italy from 493 until 553, founded by Theodoric the Great after he killed Odoacer and took Ravenna.
It was in many ways the most successful of the successor states. Roman law, the Senate, the civil administration and the consulship all continued, with a Gothic army and a Gothic king above them.
It ended in nineteen years of war with Justinian's empire, which reconquered Italy and in doing so destroyed the thing worth reconquering.
Theodoric entered Italy in 489 on the eastern emperor's commission, defeated Odoacer over four years, and killed him personally at a banquet in 493.
What followed was a deliberate division of labour. The Goths were the army and held land assignments; the Romans ran the administration, the courts and the cities, and Roman law continued to apply to them.
Theodoric ruled thirty-three years from Ravenna, corresponded with Constantinople as a legitimate authority, and left the buildings and mosaics that are the kingdom's most visible survival.
The Goths were Arian Christians and the Italian population Catholic, and for most of Theodoric's reign that difference was managed rather than fought over.
It soured at the end. Suspicion of Roman senatorial contacts with Constantinople led to the execution of Boethius around 524 — a philosopher whose Consolation of Philosophy, written in prison awaiting death, became one of the most read books of the Middle Ages.
That episode did lasting damage to the kingdom's standing with the Roman elite whose cooperation it depended on.
Theodoric died in 526 leaving a ten-year-old grandson, Athalaric, with his daughter Amalasuintha as regent — an educated, Romanised woman who governed capably and was resented for it.
Athalaric died in 534. Amalasuintha took her cousin Theodahad as co-ruler and he had her imprisoned and murdered in 535.
Justinian had been in correspondence with Amalasuintha and used her murder as his justification for war. Whether he wanted the pretext or merely accepted it is a question the sources cannot settle.
Theodoric the Great (493–526) is the kingdom in every meaningful sense: he made it, defined its settlement with the Roman population, and left it at its height.
Athalaric (526–534) reigned as a child under Amalasuintha's regency; Theodahad (534–536) murdered her, lost Sicily and Naples, and was killed by his own side for incompetence.
Vitiges (536–540) besieged Belisarius in Rome for a year and eventually surrendered at Ravenna. After a brief interval, Totila (541–552) recovered most of Italy before being killed at Taginae, and Teias (552–553) was the last king.
The kingdom ran on inherited Roman machinery: the praetorian prefecture, the tax system, the city councils and the courts continued much as before.
Cassiodorus, who served as Theodoric's minister, left a collection of official letters that is the single best window into how the administration actually worked.
The Goths were a minority — an army and a landholding class rather than a settling population — and the distance between them and the Romans, in law, religion and language, was never closed.