A steppe with size of 600 km2 in the Kherlen Bay is located in the south of Kherlenbayan Ulaan Mountain. The Conqueror Chinggis qahan Great Aurag Mansion was on the bank of Avarga River of this steppe. In this historical place, ‘The Secret Bureau of Mongolia”, which is a great fact of Mongolian history, was written. Therefore, a monument for this historical fact’s 750th Anniversary was erected in 1990. Also, this place was recorded as a national resource.