Can't believe this is still going on... X_X. ?uzumaki didn't even exist back then.
You don't get it. Rikudou was both of the clanes, but after he died the sons took each role, Elder the Uchiha and younger the Senju, which long in the future had something to do with the Uzumaki (only senju),Just because it is worded like that doesn't mean he split himself into two different people, it could simply mean that he had two sons in his life time and each one inherited different traits.
All red hairs are not Uzumaki, but all Uzumakis are red hair'ed. Got it?
Not saying Sage was an Uzumaki or not..he maybe or may not.
#truth.
How would you know? Did the manga say that? We don't know when the Uzumaki came to be, we just know they are distant relatives of the senju... How they are related, we don't know