When the Roman Empire grew too vast to be ruled from a single capital, it was split into eastern and western halves. While the western half eventually collapsed in 476 AD, the eastern half thrived. Although modern historians call this surviving eastern half the "Byzantine Empire," its citizens never used that name. They spoke Greek but passionately self-identified as Romans, using the term Romaioi.

This political shift crystallized in 330 AD, when Emperor Constantine I dedicated a grand "New Rome" on the site of Byzantium, an ancient Greek colony. This new capital, named Constantinople, occupied a highly strategic position on the Bosporus strait. Serving as a crucial transit and trade hub between Europe and Asia, the city controlled the flow of goods and wealth, which helped the Eastern Roman Empire survive long after the West fell.