By all accounts, the Buddha lived and died in India, on the other side of some very high mountain peaks. I doubt his ashes made it to China. And from what I’ve read about Buddhism, the Buddha would laugh at the idea of anyone keeping or revering his ashes.
There was a lovely story in Wikipedia about how he became deathly ill after his last meal served by a blacksmith, and how he wanted his attendants to assure the blacksmith that he hadn’t poisoned him but should be happy that he served a last meal to a Buddha. That sounds like a nice man.