The Khogno Khan mountain special protected area belongs to Khogno Khan subdistrict of Gurvanbulag district of Bulgan Province and is 46.9 sq.km. with its main feature being mountain forest zone. In this paper we present some results of research of the Anthropological and archaeological team of Mongolian Korean Joint research expeditions carryied out in Khogno Khan mountain special protected area from 27 July to 1 August, 2000. During archaeological reconnaissance we discovered around 27 localities of archaeological monuments belonging to different historical periods (from the Neolithic up to the Mongolian period, $13^{th}-17^{th}$ Century) in the territory of the Khogno Khan special protected area. Based on the results, we especially want to point out 1). The archaeological and historic monuments (from the Neolithic up to modern era) found in the Khogno Khan mountain and its surrounding area show that since the Neolithic period (around 8000 years ago) this area was occupied by the ancestors of Mongolians and it was used during subsequent historic periods on the one hand. 2). On the other hand the Khogno Khan mountain region was one area where there occurred intensive admixture between populations of Kurgan culture, Deerstone culture from the West Mongolia and the population of slab graves culture from Central and East Mongolia during Bronze and Early Iron Age. 3). Today the mountain is one of the area with a unique assemblage of archaeological monuments from different historic periods, what naturally seems like an open-air natural museum of Mongolian Prehistory.