Board Thread:General Discussion/@comment-11398218-20140704151824/@comment-4957813-20140704153607

I think Yamamoto founded the Gotei 13 as we know it, so there could've been other CCs before him. Yhwach still has Zanka No Tachi because the miracle pill Urahara used only returns Bankai if the owner takes it. Since Yamamoto couldn't take that pill due to the obstacle of being dead, Yhwach is still in possession and capable of using the Bankai.