Theoretically, all Jews are descendants of Abraham and spread to other countries in later times. In practice, of course, people marry locals wherever they go. Also, various other peoples have converted to Judaism from time to time. A couple of instances are noted in the Bible itself. In medieval times, there was a Turkic people known as the Khazars, in southern Russia (or the Ukraine), the nobility among whom converted to Judaism. The Edomites were sometimes considered Jews, as were those Samaritans Jesus talked about, though their beliefs and practices differed from the Pharisees and Sadducees and that was what all the controversy was about. More recently, a group of scientists did a DNA test of a large group of men who identified themselves as Jews, both Ashkenzai and Sephardi, and found that there were genetic markers shared by the whole group. This suggests that there was some shared ancestry, confirmation of a sort, of the Biblical story, although it does not prove the existence of a man named Abraham. There is also a group of people living somewhere around Zimbabwe which claims descent from Abraham and which DNA testing indicates has some link to the Jews of Palestine, but local admixture as well.
But when you use the word "race" you are building on shifting sand, so to speak. There is really only one race, the human race. We are all closely related, despite all the differences we think we see among ourselves, in language and ethnicity, religion, and heritage. These are really social distinctions, though, as once we are nothing but bones, it's devilishly difficult to figure out what color somebody's skin was or what language he or she spoke. So most social scientists don't much go in for using that word, "race" anymore. It's pretty obsolete. It's certainly not scientific.
MS sociology, minor anthropology