Dilmun's association with Sumer began at a very early date: a heavy concentration of early Ubaid pottery has been found in the area identified as Dilmun, on the island of Bahrein and adjacent portions of the Arabian coast. The island's springs of 'sweet water', coupled with its natural harbours, inevitably made this an important transit place for seaborne traffic from Ur, distant three days' sailing.
By the time of Sargon, when the Indus civilization (Meluhha) was also at its height, the merchants of Dilmun plied the seas between Ur, Sumer's main port, Magan (the counties at the southern end of the Persian Gulf) and Meluhha, as the distribution of their distinctive round seals attests.
Dilmun also acted as a major mercantile entrepot (trade intermediary) for traders from these regions.
After Sumer fell to the Amorites, the pattern changed: Dilmunites now conducted all the trade between Sumer and the east, but seem themselves to have obtained their trade goods from Magan.
