The Torah doesn't talk of conversion at all. It is the law for the twelve tribes of Israel, the descendants of Jacob.
Jacob's twelve sons (in order of birth), Reuben, Simeon, Levi,Judah, Dan, Naphtali, Gad, Asher, Issachar, Zebulun, Josephand Benjamin, become the ancestors of twelve tribes, with the exception of Joseph, whose two sons Mannasseh and Ephraim, who were adopted by Jacob, become tribal eponyms (Genesis 48). https://en.wikipedia.org/wiki/Israelites
They are "the people" whom God favours.
It was Christianity that sought converts.