Throughout its history, its borders were ever fluctuating, often involved in multi-sided conflicts with not only the Arabs, Persians and Turks of the east, but also with its Christian neighbours- the Bulgarians, Serbs, Normans and the Crusaders, which all at one time or another conquered large amounts of its territory. By the end, the empire consisted of nothing but Constantinople and small holdings in mainland Greece, with all other territories in both the Balkans and Asia Minor gone. The conclusion was reached in 1453, when the city was successfully besieged by Mehmet II, bringing the Second Rome to an end.