The old woman is recalling what her daughter said before leaving the village. I understand
"Whatever it's a person from inside the village or outside it doesn't matter"
"Such power exists inside the kagura and the dance."
However what I'm stumbled is the middle sentence
"1つになる" may be modifying 神楽 and 歌 but I'm not convinced. Likely it may say that the people outside and inside became one under that power.
However, I'm stumbled of the meaning of くるりと回れば
Either she's talking about the dance she performs, or it's "after seeing the world" or some nuance I'm missing.
She should be saying that the Kagura and the dance don't discriminate and they have the power to unify people.