Which civilization was the first to develop a monotheistic religion?

I may be wrong but I believe the first move towards a monotheistic religion was made by Akhenaten, an Egyptian Pharoah. He went against the contemporary trend of many gods, even going so far as building a new city dedicated to the worship of the one god, the sun god Aten out in the desert. This move so infuriated the powerful priests of the time that after his death (under extremely murky circumstances) they set about totally obliterating all record and memory of his reign and were so successful at it that the existence of Akhenaten was only relatively recently unearthed.