In European history, the thousand-year span between the fall of the Roman empire and the Renaissance beginnings of modern history is known as the Middle Ages. Perhaps best remembered today for knights on horseback and towering Gothic cathedrals, this medieval period began with the collapse of the western Roman empire.
King Clovis of the Franks rallies his warriors during one of many battles he fought to build his kingdom. His conversion to Christianity set an example for other Germanic rulers.
You have read that as German invaders pounded the Roman empire in the west, the Roman emperor Constantine and his successors shifted their base to the eastern Mediterranean. Constantine rebuilt the Greek city of Byzantium and then renamed it after himself—Constantinople. By 330, he made Constantinople the new capital of the empire. From this “New Rome,” roads fanned out to the Balkans, to the Middle East, and to North Africa. In time, the eastern Roman empire became known as the Byzantine empire.
The vital center of the empire was Constantinople. The city was located on the shores of the Bosporus, a strait that links the Mediterranean and Black seas. Constantinople had an excellent harbor and was guarded on three sides by water. Emperors after Constantine built an elaborate system of land and sea walls to bolster its defenses.
Equally important, Constantinople commanded key trade routes linking Europe and Asia. For centuries, the city's favorable location made it Europe's busiest marketplace.