The Roman Empire underwent considerable social, cultural and organizational change starting with reign of Diocletian, who began the custom of splitting the Empire into Eastern and Western halves ruled by multiple emperors. Beginning with Constantine the Great the Empire was Christianized, and a new capital founded at Constantinople. Migrations of Germanic tribes disrupted Roman rule from the late 4th century onwards, culminating in the eventual collapse of the Empire in the West in 476, replaced by the so-called barbarian kingdoms. The resultant cultural fusion of Greco-Roman, Germanic and Christian traditions formed the cultural foundations of Europe.