Territorial evolution of the Ottoman Empire

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The territorial evolution of the Ottoman Empire spans seven centuries.

The origins of the Ottomans can be traced back to the late 11th century when a few small Muslim emirates of Turkic origins and nomadic nature—called Beyliks—started to be found in different parts of Anatolia. Their main role was to defend Seljuk border areas with the Byzantine Empire —a role reinforced by the migration of many Turks to Asia Minor.^[1] However, in 1071 and following the victory of the Sultanate of Rum over the Byzantines at the Battle of Manzikert, Beyliks sought an opportunity to override the Seljuk authority and declare their own sovereignty openly.

While the Byzantine Empire was to continue for nearly another four centuries, and the Crusades would contest the issue for some time, the victory at Manzikert signalled the beginning of Turkic ascendancy in Anatolia. The subsequent weakening of the Byzantine Empire and the political rivalry between the Seljuk Sultanate of Rum and the Fatimids in Egypt and southern Syria were the main factors that helped the Beyliks take advantage of the situation and unite their principalities.^[2]

Among those principalities was a tribe called Söğüt, founded and led by Ertuğrul, which settled in the river valley of Sakarya. When Ertuğrul died c. 1280 his son Osman succeeded him, establishing the state which would go on to become the Ottoman Empire.