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.

EDIT: in case people want to know:

Son Goku (4 tails) is known as the Great Sage Equalling heaven and as the "King of the Sage Monkeys". Which kind of implies there are Sage Monkeys, but then Son shows no real Sage Mode power so it's not clear if this is meant as a literal Sage.