What was the Byzantine empire that could not sustain control of the Western Empire also known as?
In 376, the Goths, fleeing from the Huns, received permission from Emperor Valens (r. 364–378) to settle in the Roman province of Thracia in the Balkans. The settlement did not go smoothly, and when Roman officials mishandled the situation, the Goths began to raid and plunder. Valens, attempting to put down the disorder, was killed fighting the Goths at the Battle of Adrianople on 9 August 378. As well as the threat from such tribal confederacies from the north, internal divisions within the empire, especially within the Christian Church, caused problems. In 400, the Visigoths invaded the Western Roman Empire and, although briefly forced back from Italy, in 410 sacked the city of Rome. In 406 the Alans, Vandals, and Suevi crossed into Gaul; over the next three years they spread across Gaul and in 409 crossed the Pyrenees Mountains into modern-day Spain. The Migration Period began, when various peoples, initially largely Germanic peoples, moved across Europe. The Franks, Alemanni, and the Burgundians all ended up in northern Gaul while the Angles, Saxons, and Jutes settled in Britain, and the Vandals went on to cross the strait of Gibraltar after which they conquered the province of Africa. In the 430s the Huns began invading the empire; their king Attila (r. 434–453) led invasions into the Balkans in 442 and 447, Gaul in 451, and Italy in 452. The Hunnic threat remained until Attila's death in 453, when the Hunnic confederation he led fell apart. These invasions by the tribes completely changed the political and demographic nature of what had been the Western Roman Empire.By the end of the 5th century the western section of the empire was divided into smaller political units, ruled by the tribes that had invaded in the early part of the century. The deposition of the last emperor of the west, Romulus Augustulus, in 476 has traditionally marked the end of the Western Roman Empire. By 493 the Italian peninsula was conquered by the Ostrogoths. The Eastern Roman Empire, often referred to as the Byzantine Empire after the fall of its western counterpart, had little ability to assert control over the lost western territories. The Byzantine emperors maintained a claim over the territory, but while none of the new kings in the west dared to elevate himself to the position of emperor of the west, Byzantine control of most of the Western Empire could not be sustained; the reconquest of the Mediterranean periphery and the Italian Peninsula (Gothic War) in the reign of Justinian (r. 527–565) was the sole, and temporary, exception.
Eastern Roman Empire