Briefly, we know Aryans are the ones who united China. Likely some of the first emperors who moved them from tribes to feudal states. Somewhere along the lines, the Japanese broke off. Basically the Japanese are fairly close to what the Chinese were before their four purges. Imoho, their purges were really about removing Aryan influence and genetics. I might be wrong on that too. Just conjecture. Regardless, I fully expect there have been multiple points in time in which Aryan genetics are injected into various Asian populations. Including China and japan.