The eastern half of the Roman Empire—the Byzantine Empire—thrived at the crossroads of trade linking Europe, Asia, and Africa. With a diverse population, it blended Greek and Roman thought, Christian belief, and cultural influences from Persia and other areas of the Middle East. There was ongoing hostility between the two separate bodies of Christianity—the Roman Catholic Church in western Europe and the Eastern Orthodox Church in the Byzantine Empire. Until 1453, the Byzantine Empire held out against a series of invaders that included Persians, Arabs, and western European Crusaders. Byzantine culture had a lasting effect on such neighboring peoples as the Slavs of eastern Europe, who were converted by Byzantine missionaries to Christianity. The development of Kiev in Ukraine became the foundation for civilizations in Ukraine, Belarus, and Russia.