Persia is first attested in Assyrian sources from the third millennium BC in the Old Assyrian form , designating a region belonging to the Sumerians. The name of this region was adopted by a nomadic ancient Iranian people who migrated to the region in the west and southwest of Lake Urmia, eventually becoming known as the Persians. The ninth-century BC Neo-Assyrian inscription of the Black Obelisk of Shalmaneser III, found at Nimrud, gives it in the Late Assyrian forms and as a region and a people located in the Zagros Mountains, the latter likely having migrated southward and transferred the name of the region with them to what would become Persis (Persia proper, i.e., modern-day Fars), and that is considered to be the earliest attestation to the ancient Persian people.