Board Thread:Theories and Speculation/@comment-1932060-20171201013626/@comment-734582-20171202073058

It's been vague for a while whether the Monkeys are sages too, but it could be true. Hashirama had Hiruzen (a Monkey summoner) as his student, so he could've gotten in contact with them that way (or alternatively, that's how Hiruzen got his monkey).

So...plausible theory i guess? Don't really see how we'd ever confirm this beyond straight up asking Kishimoto though.