1.The sage was a priest.
2.priest use funinjustu
3.The sage after sealing the juubi had two sons
They went onto carry certain traits the uchiha ancestor gaining the sages spiritual energy and the chakra of the juubi
The senju ancestor (Uzumaki) gained the psyhical energy of the sage (The body)
4.
The uzumaki are known for Funinjustu a.k.a. SEALING JUSTU and have a strong vitality which has been shown when all uzumaki who have been jinchuuriki survived the extraction and live long lives.
4.B
The sages son believed in peace so the uzumaki son kept close ties with his descendants the senju and when kurama needs a jinchuriki who is always there to become the host ?
Was it a senju ? No ? Was it a uchiha ? Nope.
It was an uzumaki every time.
5.
They are distant relatives not direct descendants of the senju
6.
Rinnegan requires the progenitor genes.
These genes cannot be replicated.
You need the exact dna to make the rinnegan surface.
Uchiha + Senju = rinnegan
Oh but wait nagao doesn't have senju dna so how is that possible ?
Oh wait because he already has the required dna because he is an uzumaki.
If they were descendants then the genes would be diluted and any uzumaki would still need senju dna.
The uchiha dna was already provided through the rinnegan because the rinengan was formed from the sharingan.
/////thread
