Was the center of the Xiongnu Empire in the Orkhon valley

Bonn : Xiongnu archaeology. Multidisciplinary Perspectives of the First Steppe Empire in Inner Asia. 2011. - p. 441-461 The Orkhon valley was the cradle of the formation of many rider-nomad domains and empires, the heartland and center of mounted nomadic peoples like the Xiongnu, Kok-Turk, Uighurs and Mongols. It is the Otukan area, the sacred promised land of the Old Turkic royal ideology, where according to tradition already the Xiongnu and Uighurs had their capital, the Kok-Turk their center of cult and authority.