The word exists in many languages today with shades of related meanings. No doubt original source is Sumerian which was language isolate. Don't remember the book's name but I may have it referenced in an old email. It clearly said Ur-du in Sumerian means going away from Ur. People ignore the third wife Kethura r.a. of Prophet Ibrahim a.s. I will try to post a video of a Jewish rabbi, they know some of Prophet Ibrahim's descendants from her spread to India (including Pakistan and Afghanistan). But he had them confused with Brahman who are Aryans originating in southern Russia. Sanskrit is native Aryan Brahman language, but it is not native language of the original Kshatriya.