Ufa (Öfö; Уфа́) is the largest city in and the capital of Bashkortostan, Russia. The city lies at the confluence of the Belaya and Ufa rivers, in the centre-north of Bashkortostan, on hills forming the Ufa Plateau to the west of the southern Ural Mountains, with a population of over 1.1 million residents, up to 1.4 million residents in the urban agglomeration. Ufa is the tenth-most populous city in Russia, and the fourth-most populous city in the Volga Federal District. The city is considered to have been founded in 1574, when a fortress was built on the site of the city by order of Ivan the Terrible. Ufa was made capital of Ufa Governorate in 1865 when the governorate split from Orenburg Governorate. Ufa's population expanded during the early 20th century. Today, Ufa's economy consists primarily of the oil refining, chemistry, and mechanical engineering industries; the petroleum company Bashneft and several of its subsidiaries are headquartered in Ufa. Ufa is an ethnically diverse city, home to a substantial number of ethnic Bashkirs and Tatars, with an ethnic Russian majority population. Several educational institutions are located in Ufa, including Bashkir State University, Ufa State Aviation Technical University, Ufa State Petroleum Technological University, and Ural State Law University. The city hosted separate summits of the BRICS group as well as the Shanghai Cooperation Organisation in 2015. The name Ufa comes from the Ufa River on which the city lies, but the origin of the river's name is disputed. The Russian linguist Aleksandr Matveyev proposes that the name is of Iranian origin, from "ap", meaning water. In a paper published in 2014, researchers Karimov and Khabibov from Bashkir State Pedagogical University present and argue for a hypothesis according to which before the construction of the foundational Russian fortress in 1574, which has since grown to become the current city of Ufa, there had already been an ancient settlement called Ufa on a hilltop near the mouth of the Ufa River.