The Byzantine Empire, also referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinople. It survived the fragmentation and fall of the Western Roman Empire in the 5th century AD and continued to exist for an additional thousand years until it fell to the Ottoman Turks in 1453. During most of its existence, the empire remained the most powerful economic, cultural, and military force in Europe. The term 'Byzantine' was coined by later historians to distinguish the medieval state from the ancient Roman Empire, but its citizens continued to refer to themselves as 'Romans' (Romaioi). The empire's history is marked by cycles of decline and recovery. Under Justinian I (r. 527โ565), the empire reached its greatest extent after reconquering much of the historically Roman western Mediterranean coast, including North Africa, Italy, and Rome itself. The empire faced significant challenges, including the Persian and Arab wars in the 7th century which cost it its richest provinces (Egypt and Syria), the Iconoclastic Controversy, and the rise of the Seljuk Turks. However, it experienced a resurgence during the Macedonian dynasty (10thโ11th centuries) and the Komnenian restoration (12th century). The Fourth Crusade in 1204, which sacked Constantinople, dealt a devastating blow from which the empire never fully recovered, leading to its final fall in 1453.