The article considers the materials of the Urd Ulaan Uneet cave burial, investigated in 2015. This complex is located in the Tsagaanbulag Myangad Somon of Kobdo Aimak of Mongolia, at the altitude of 1327 m a.s.l. Pre-sented is the description of the circumstances of discovery of this important site, as well as the existing experi-ence of studying and publishing of the materials. The main objective of the study is the detailed analysis of the main categories of finds from the cave burial, the most informative of which include wooden saddle, iron bits with horn psalia, compound bow, arrowheads, leather quiver with iron hook, and wooden vessel. For the interpretation of these items, extensive archaeological sources of the Syanby-Rouran and medieval time, assembled during the excavations in various parts of the Central Asian region, were involved. Based on the results obtained, a number of conclusions have been made regarding the cultural and chronological interpretation of the site. It has been established that the Urd Ulaan Uneet complex is one of the rare objects of the Rouran time in Mongolia, and the only known cave burial of this chronological period. The monument can be confidently dated to the middle of the 4th –5th c. AD with the possible extension of the upper chronological boundary to the beginning of the 6th c. AD. This conclusion is generally supported by the results of radiocarbon analysis presented in the publications of Mongolian archaeologists. An indicative characteristic of the cave site, not revealed during the excavations of other objects of the Rouran period in Mongolia, is the accompanying burial of a horse. Obviously, this feature of the funeral rite is explained by contacts with the population of the Bulan-Koby Culture. The weighty argument in favor of the proposed possible interactions between the Altai cattle breeders and nomads of Western Mongolia in the Rouran period could be found among the investigated burials of the Bulan-Koby Culture in the Bayan-Ulgiy Aimag. The material complex found during the excavation of the Urd Ulaan Uneet cave burial reflects the very wide contacts of the population of Mongolia in various directions (Altai-Sayan Region, Trans-Baikal Region, Man-churia, East Turkestan, Central Asia) in the middle of the 1st mil. AD. In addition, the «western» relations are clearly distinguishable; these obviously demonstrate the complex migration processes of the Great Migration Period.