The Byzantine empire officially ended with the siege of Constantinople that happened in 1453 by the Ottomans Turks. When the city fell, the Ottomans took the former Byzantine territories and dominated southeastern Europe, rising economically and religiously.
The fall of the Byzantine empire had a special meaning, it was the capital of the Catholic Church on the Roman Empire when Constantinople fell for the hands of the Turks it meant that Islam was the main religion.
