Mesopotamian trade documents, lists of goods, and official inscriptions mentioning Meluhha supplement Harappan seals and archaeological finds. Literary references to Meluhhan trade date from the Akkadian, the Third Dynasty of Ur, and Isin-Larsa Periods (c. 2350–1800 BC), but the trade probably started in the Early Dynastic Period (c. 2600 BC). Some Meluhhan vessels may have sailed directly to Mesopotamian ports, but by the Isin-Larsa Period, Dilmun monopolized the trade. The Bahrain National Museum assesses that its "Golden Age" lasted ca. 2200–1600 BC. Discoveries of ruins under the Persian Gulf maybe of Dilmun.