An island in the Persian Gulf that has been identified with the ancient land of Dilmun (Telmun) of about 2000 BC, a prosperous trading center linking Sumeria with the Indus Valley. Written records of the archipelago exist in Assyrian, Persian, Greek, and Roman sources. Burial mounds in the north of Bahrain Island suggest a period of Sumerian influence in the 3rd millennium BC. There are densely packed fields of tumuli in Bahrain and at several places on the adjacent mainland. They are associated with densely packed complexes of cist burials. Excavation has shown the island to be an important link in the sea trade between that region and the Indus civilization. Two important sites in the north of the island belong to the 'Dilmun period': a walled town at Qala'at al-Bahrain and a complex temple building at Barbar. Among the finds of this period are circular steatite stamp 'Persian Gulf' seals, related to Indus Valley seals, but probably made locally.