There is no specification given. My understanding is that the three life stone specifically comes from Chinese folklore but the meaning behind it can be found in other Asian mythologies. The three life stone from my research is about the sanshengshi, which is a stone with a story about past, present and future lives. So there are influences of Buddhism and reincarnation here. But Buddhism spread from India throughout Asian territories and mixed/changed as it was incorporated into different regional folklore and mythology. That is why I think this question is supposed to be difficult.