There was a time when Western classicists and metaphysicians searched high and low for the primordial or original religion: Ur-monotheismus. The thinking was that the original religion was monotheistic and that all non-monotheistic religions had degenerated from the pristine original.
This is of course precisely backwards but it has not stopped the search. While Ur-religionists chase ghosts, the rest of us can fret over the dismal fate of the actual Sumerian city-state of Ur, which remains largely buried — and 90% unexcavated — in the Iraqi desert.
While this may or may not have been the birthplace of Abraham, its importance for the history of religions extends far beyond its status as mythical nursery for monotheism.
Ur is frequently used as a prefix for all that is supposedly seminal. What little we know about its religion hearkens back to the shamanic and Paleolithic past while simultaneously systematizing polytheism and moving toward monotheism. I find it incredible that such riches are buried in the sand waiting to be discovered. Ur-gh.