Board Thread:Theories and Speculation/@comment-1872728-20160229033316/@comment-18497248-20160229041351

There is no main and branch here, they are two seperate clans. They are simply related by a common ancestor. Also, the Uchiha being a branch clan makes no sense, only they come from Indra, there's no other clan of his for them to branch off of.

If you want to be technical, all of these clans are branches of the Ōtsutsuki that eventually became distant enough to be their own thing.