Since the discovery in 1966 of the Gm ab3st gene, which characterizes Mongoloid populations, the distribution of allotypes of immunoglobulins (Gm) among Mongoloid populations scattered from Southeast Asia through East Asia to South America has been investigated, and the following conclusions can be drawn: 1. Mongoloid populations can be characterized by four Gm haplotypes, Gm ag, axg, ab3st, and afb1b3, and can be divided into two groups based on the analysis of genetic distances utilizing Gm haplotype frequency distributions: the first is a southern group characterized by a remarkably high frequency of Gm afb1b3 and a low frequency of Gm ag, and the second, a northern group characterized by a high frequency of both Gm ag and Gm ab3st but an extremely low frequency of Gm afb1b3. 2. Populations in China, mainly Han but including minority nationalities, show remarkable heterogeneity of Gm allotypes from north to south and contrast sharply to Korean and Japanese populations, which are considerably more homogenous with respect to these genetic markers. The center of dispersion of the Gm afb1b3 gene characterizing southern Mongoloids has been identified as the Guangxi and Yunnan area in the southwest of China. 3. The Gm ab3st gene, which is found with its the highest incidence among the northern Baikal Buriats, flows in all directions. However, this gene shows a precipitous drop from mainland China to Taiwan and Southeast Asia and from North to South America, although it is still found in high frequency among Eskimos, Koryaks, Yakuts, Tibetans, Olunchuns, Tungus, Koreans, Japanese, and Ainus. On the other hand, the gene was introduced into Huis, Uyghurs, Indians, Iranians, and spread as far as to include Hungarians and Sardinians in Italy. On the basis of these results, it is concluded that the Japanese race belongs to northern Mongoloids and that the origin of the Japanese race was in Siberia, and most likely in the Baikal area of the Soviet Union.