They aren't racially homogeneous though. The Ainu, Ōbeikei, Nivkh, Yamato and Ryukyuans aren't ethnically or even racially the same at all. Obeikei are closer to Pac Islanders, Ainu are closer to Inuit and Nivkh are closer to Asian Russian. Yamato are the largest demographic but even with them there's some contention since there's different looks so some suspect that some Yamato are closer to Chinese in origin and some are closer to Mongolian in origin. There were disagreements about considering the Ryukyuan's are the same as the Yamato, or identify them as an independent but related ethnic group, or as a sub-group that constitutes Japanese ethnicity together with the Yamato but recent genetic studies say the Ryukyuan people share more alleles with the southern Jōmon (16,000–3,000 years ago) hunter-gatherers than the Yamato Japanese, have smaller genetic contributions from Asian continental populations, which supports the dual-structure a widely accepted theory which suggests that the Yamato Japanese are more admixed with Asian agricultural continental people (from the Korean Peninsula) than the Ainu and the Ryukyuan's, with major admixture occurring in and after the Yayoi period (3,000-1,700 years ago).

they are not racially homogenous holy shit. you dont know anything about india