between 1191 and 1200.
Theodosiopolis repelled many attacks and military campaigns by the Seljuks and Georgians (the latter knew the city as Karnu-Kalaki) until 1201 when the city and the province was conquered by the Seljuk sultan Süleymanshah II. Erzen-Erzurum fell to the Mongol siege in 1242, and the city was looted and devastated. After the fall of the Seljuk Sultanate of Anatolia (Rüm) in early 14th century, it became an administrative province of the Ilkhanate, and after their fall, became part of the Çobanbeylik, Black Sheep Turkmen, empire of TimurLenk and White Sheep Turkmen. Finally, in 1514 the region was conquered by the Ottoman Sultan Selim I, so called Selim the Inflexible. During the Ottoman Empire reign, the city served as the main base of Ottoman military power in the region.
It served as the capital of the eyalet of Erzurum. Early in the seventeenth century, the province was threatened by Safavid Persia and a revolt by the province governor AbazaMehmed Pasha. This revolt was combined with Jelali Revolts (the uprising of the provincial musketeers called the Jelali), backed by Iran and lasted until 1628.
Modern history
The city was captured by the Russian Empire in 1829, but was returned to the Ottoman Empire under theTreaty of Adrianople (Edirne), in September of the same year. During the Crimean war Russian forces approached Erzurum, but did not attack it because of insufficient forces and the continuing Russian siege ofKars. The city was unsuccessfully attacked (Battle of Erzurum (1877)) by a Russian army in the Russo-Turkish War of 1877-78. However in February 1878, the Russians took Erzurum without resistance, but it was again returned to the Ottoman Empire, this time under the Treaty of San Stefano. There were massacres of the city's Armenian citizens during the Hamidianmassacres(1894–1896). The city was the location of one of the key battles in the Caucasus Campaign of World War I between the armies of
