The Mink Tribe is known to stretch back to before the void century. It's likely that events of the Void Century affected the Minks (left them living on Zou, also from before the Void Century), and also the Oni (driving them close to extinction?). If that's the case, then there could be reason for both Carrot and Yamato to go to Laughtale (unless Oden's journal holds the true history in it, obviously).