Erzurum is a city in Eastern Anatolia, Turkey. It is the capital of Erzurum Province, the largest province in Turkey's Eastern Anatolia Region. The city is situated 1757 meters (5766 feet) above sea level. Erzurum had a population of 361,235 in the 2000 census. (by 2010 it increased to 367,250).

Erzurum, known as "The Rock" in NATO code, served as NATO's southeastern-most air force post during the Cold War. The city uses the double-headed Anatolian Seljuk Eagle as its coat-of-arms, a motif based on the double-headed Byzantine Eagle that was a common symbol throughout Anatolia and the Balkans in the medieval period.

Erzurum has some of the finest winter sports facilities in Turkey and hosted the 2011 Winter Universiade.

The name "Erzurum" derives from "Arz-e Rum" (literally The Land of the Romans in Arabic). In ancient times, Erzurum existed under the Armenian name of Karin. During the reigns of the Artaxiad and Arsacid kings of Armenia, Karin served as the capital of the eponymous canton of Karin. After the partition of Armenia between the Roman Empire and Sassanid Persia in 387 AD, the city passed into the hands of the Romans. They fortified the city and renamed it Theodosiopolis, after Emperor Theodosius I. As the chief military stronghold along the eastern border of the empire, Theodosiopolis held a highly important strategic location and was fiercely contested in wars between the Byzantines and Persians. Emperors Anastasius I and Justinian I both refortified the city and built new defenses during their reigns.

The Seljuk era Chifte Minareli Medrese (Twin Minaret Madrasa) is the symbol of the city and appears on its coat of arms. Theodosiopolis was conquered by the Umayyad general Abdallah ibn Abd al-Malik in 700/701. It became the capital of the emirate of Qaliqala and was used as a base for raids into Byzantine territory. Though only an island of Arab power within Christian Armenian-populated territory, the native population was generally a reliable client of the Caliph's governors. As the power of the Caliphate declined, and the resurgence of Byzantium began, the local Armenian leaders preferred the city to be under the control of powerless Muslim emirs rather than powerful Byzantine emperors.

In 931, and again in 949, Byzantine forces led by Theophilos Kourkouas, grandfather of the future emperor John I Tzimiskes, captured Theodosiopolis. Its Arab population was expelled and the city was resettled by Greeks and Armenians. Emperor Basil II rebuilt the city and its defenses in 1018 with the help of the local Armenian population. In 1071, after the decisive battle at Manzikert, the Seljuk Turks took possession of Theodosiopolis. The Saltuklus were rulers of an Anatolian beylik (principality) centered in Erzurum, who ruled from 1071 to 1202. Melike Mama Hatun, sister of Nasiruddin Muhammed, was the ruler 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 Suleymanshah 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 (Rum) in early 14th century, it became an administrative province of the Ilkhanate, and after their fall, became part of the Choban beylik, Black Sheep Turkmen, empire of Timur Lenk 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 was 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 Abaza Mehmed Pasha. This revolt was combined with Jelali Revolts (the uprising of the provincial musketeers called the Jelali), backed by Iran and lasted until 1628.

The city was captured by the Russian Empire in 1829, but was returned to the Ottoman Empire under the Treaty 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 of Kars. 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 Hamidian massacres (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 the Ottoman and Russian Empires. This resulted in the capture of Erzurum by Russian forces under the command of Grand Duke Nicholas and Nikolai Nikolaevich Yudenich on February 16, 1916.

Erzurum was also a major deportation center during the Armenian Genocide in 1915. In the late April 1915, about 450 prominent Armenians of Erzerum city were imprisoned. Most of them were intellectuals,community leaders, journalists and merchants. In early May 1915 they were all executed. Prior to the war, the city had a vibrant Armenian community with numerous schools and served as the provincial residence of the Archbishop of the Armenian Apostolic Church. By the time the Russians entered in 1916, barely a hundred Armenians were left alive, out of a prewar population of 20,000; it is estimated that approximately 90% of the Armenians of Erzurum province had perished. By 1919, according to the American Committee for Relief in the Near East, Erzurum was left completely devoid of its Armenian population. It is reported in Turkish sources that some Armenian troops serving in the Russian army carried out revenge killings in the area of Erzurum, after having witnessed the destruction that had been wrought against the Armenian population.

Erzurum reverted to Ottoman control after the signing of the Treaty of Brest-Litovsk in March 1918. In 1919, Mustafa Kemal Ataturk, one of the key founders of the modern Turkish Republic, resigned from the Ottoman Army in Erzurum and was declared an "Honorary Native" and freeman of the city, which issued him his first citizenship registration and certificate (Nufus Cuzdani) of the new Turkish Republic. The Erzurum Congress of 1919 was one of the starting points of the Turkish War of Independence.