Of course, this was just a suspicion; he wasn't an expert in ancient scripts, so his judgment might not be correct, but these characters seemed very familiar to him. For example, there was a character that the Ainu people often drew on their bodies, which looked a lot like the primitive version of "Su," probably meaning "virtue" or "land of virtue," and many of the characters resembled the inscriptions on the Terracotta Warriors; at least some of the radicals were quite similar—as if they shared the same origin or had influenced each other.
But the Ainu didn't look like Chinese people at all: their skin was white, they were hairy, and the men sported big, curly beards—actually, they looked a bit like Russians.
Maybe they were mixed-blood?