Dilmun

Dilmun is a land mentioned by Mesopotamian civilizations. It was a trade partner, a source of the metal copper, and an entrepôt of the Mesopotamia-to-Indus Valley Civilization trade route. Although the exact location of Dilmun is not known, it was most likely located in the islands of Bahrain and Failaka island, Kuwait. Dilmun had a presence in the Eastern Province of Saudi Arabia, Qatar, Oman and nearby Iranian coast in the Persian Gulf. Gilgamesh had to pass through Mount Mashu to reach Dilmun in the Epic of Gilgamesh.
Dilmun appears first in Sumerian cuneiform clay tablets from the end of fourth millennium BC.