The desire of the Ghazi Turks to expand their territory under Osman I early in the 14th century led to the rise of the Ottoman Empire. These Islamic raiders attracted hordes of nomadic peoples to bolster their army and successfully assaulted the decaying defenses of the Byzantine Empire in Anatolia.
The ancestors of the Ghazis were tribal nomads who fled from Genghis Khan's Mongols and settled in Anatolia in the 12th century. The word "Ottoman" comes from the name "Osman." After Osman I united the Ghazis, they attacked the Byzantines but bypassed the capital, Constantinople. After the death of Osman I, the Ottomans expanded into the Balkans and Eastern Europe. They captured Thessaloniki from the Venetians in 1387 and Kosovo from the Serbs in 1389. The European crusades of the Middle Ages failed to vanquish them. Finally, in 1453, the Ottomans overcame the heavily fortified city of Constantinople. In the 15th and 16th centuries, further conquests expanded the territory of the Ottoman Empire into Syria, Egypt, Somalia, Mesopotamia, Greece and parts of Hungary.
Though weakened by a series of military defeats in the 17th and 18th centuries, the Ottoman Empire continued to exist until the end of World War I, when it was dissolved by the Treaty of Sevres. It was one of the most powerful and long-lasting empires in history.