By the reign of the emperor Justinian I (ruled 527-565 CE), the vast territories of the Roman Empire in Europe, North Africa, and the East had for centuries been politically and culturally divided into the Western Empire and the Eastern, or Byzantine, Empire. The Western Empire had endured a series of Germanic invasions that led to its final collapse by 476 CE. So the Roman Empire under Justinian's rule was the East – though during his reign, the emperor waged a successful campaign to reconquer some of the Western territories that had been lost to Germanic invaders, such as Italy and parts of Spain. Like other Roman emperors before him, Justinian faced the challenge of maintaining control and creating a sense of unity among far-flung territories where other cultures and languages besides Latin (such as Greek) predominated.