Since 2004 Mongolian-Russian joint expedition have been carried out archaeological excavation of the some Qidan(契丹) settlements, fortresses in the area of Bulgan and Tuv aimag in Mongolia. During the expedition in Tuul river valley from ruins of the 10-11 century settlement sites were found some archaeological finds associated with Balhae(渤海) culture. Practically and scientifically very interesting that found Balhae period archaeological discovery on the territory of Mongolia. As we know Balhae settled in present-day Russia’s Far East, Primorskii territory and eastern China. In this article we concluded materials, artifacts from Chin tolgoi, Tsagaan denjiin balgas and Emgentiin herem, which are commonly associated with Balhae culture. We have a question: When and why in the territory of Mongolia settled Balhae people. This is due to military policy of Qidan. From 10th to the 12th century into the territory of present-day Mongolia housed many Qidan soldiers, established their own military district and formed own policy. In “History of the Liao dynasty(遼)” mention, that on the territory of Mongolia however Qidan settled Balhae and Zurchid people. In Tuul river valley until nowadays preserved cultural monuments with a special Balhae ornament and decoration. Balhae people, who migrated to the territoryof Qidan and build houses, palaces, produced pottery and etc., on their own technology. Most Balhae people were craftsmen, blacksmiths and of course peasants. And their knowledge of agriculture and craft is bearing on the Mongols. Cultural relation between Balhae or Korean and Mongolian people have not been clarified. Balhae archaeological finds from the territory of Mongolia confirmed that Mongolia had a significantly long economic and cultural relation with Korea. On the other hand, the eastern boundary of culture Balhae becomes Gobi and the Khangai mountains, thus limit the spread of culture Balhae much wider. These sites confirm that the archaeological side, you can update the date of the foreign relations of the ancient Mongolia and Korea.