a date of 395. However, historian Iaroslav Lebedynsky and archaeologist Katalin Escher prefer an estimate between the 390s and the first decade of the fifth century. Several historians have proposed 406 as the date. Attila grew up in a rapidly changing world. His people were nomads who had only recently arrived in Europe. They crossed the Volga river during the 370s and annexed the territory of the Alans, then attacked the Gothic kingdom between the Carpathian mountains and the Danube. They were a very mobile people, whose mounted archers had acquired a reputation for invincibility, and the Germanic tribes seemed unable to withstand them. Vast populations fleeing the Huns moved from Germania into the Roman Empire in the west and south, and along the banks of the Rhine and Danube. In 376, the Goths crossed the Danube, initially submitting to the Romans but soon rebelling against Emperor Valens, whom they killed in the Battle of Adrianople in 378. Large numbers of Vandals, Alans, Suebi, and Burgundians crossed the Rhine and invaded Roman Gaul on December 31, 406 to escape the Huns. The Roman Empire had been split in half since 395 and was ruled by two distinct governments, one based in Ravenna in the West, and the other in Constantinople in the East. The Roman Emperors, both East and West, were generally from the Theodosian family in Attila's lifetime (despite several power struggles). The Huns dominated a vast territory with nebulous borders determined by the will of a constellation of ethnically varied peoples. Some were assimilated to Hunnic nationality, whereas many retained their own identities and rulers but acknowledged the suzerainty of the king of the Huns. The Huns were also the indirect source of many of the Romans' problems, driving various Germanic tribes into Roman territory, yet relations between the two empires were cordial: the Romans used the Huns as mercenaries against the Germans and even in their civil wars. Thus, the usurper Joannes was able to recruit thousands of Huns for his army against Valentinian III in 424. It was Aëtius, later Patrician of the West, who managed this operation. They exchanged ambassadors and hostages, the alliance lasting from 401 to 450 and permitting the Romans numerous military victories. The Huns considered the Romans to be paying them tribute, whereas the Romans preferred to view this as payment for services rendered. The Huns had become a great power