This is a review using archaeological and scientific evidence to explain why tin bronze is of limited distribution in Southwest Asia and the East Mediterranean in the third millenium. Chemical analytical data on bronzes from the area is discussed and shows the sporadic appearance of tin bronze in Iran and regular use in Mesopotamia, against the current view of the universal use of arsenical copper in the region at this time. Tin was originally a status metal because of its variety and distant source. Its trade reinforced the special status of the Sumerians and Akkadians, and it occurs in their area of influence. Silver and gold artifacts, and their compositions, are also discussed. -- AATA