Anthropologically, the Thai peoples are variants of the South-Mongoloid type. Some Thai peoples (Lao, Nung, Thais) show some features of the so-called "Veddoid type" - the Negroid-Australoid race. The Thai peoples are part of an even larger family of Ai-Kadai peoples. The migration of ancient Thai tribes to Southeast Asia began in the last centuries of the 1st millennium BC, presumably from Central Asia. In the 3rd - 1st centuries B.C. the megalithic culture of the early Iron Age is spreading, maybe connected with the penetration of Thai tribes into this area. At the beginning of our era there was a state formation or rather a union of Lao tribes belonging to the same Thai group and subsequently subjected to the cultural influence of India. Migration intensified in the first centuries A.D. as new nomadic tribes came in from the north and ended in the 13th century when the Mongols, having established their power in the territory of China, ousted part of the Lao Tai tribes from the territory of modern Chinese province Yunnan.