Disclaimer: This theory was not thought of by me. I just highly updated and modified it. X Not much is known about the Uzumaki clan, however we do known Naruto's mother was from the Uzumaki clan, as well as the Whirlpool Country. The Whirlpool Country invaded by the bloody mist which was controlled by none other than Madara Uchiha(He controlled Yagura, the mizukage). Kushina Uzumaki was from the ruling family of the Uzumaki clan, she was saved from certain death before the invasion & taken to Konoha to X with her distant cousins the Senjus. Hashirama has an Uzumaki wife. It is not far-fetched to say that the Senju and Uzumaki are related. After all, why would a senju member a non-senju. Uchiha only married Uchiha and it was the same way for other clans. The Uzumaki carry a certain kekkei genkai that we witnessed early in the manga. Did you ever notice anything interesting about the Senju?