Hyrcanian plain
The Hyrcanian plain () was a plain near Sardis, the provincial capital of the Achaemenid Persian satrapy (province) of Lydia. Located in the Hermos valley, in what is present-day western Turkey, according to the ancient geographer and historian Strabo, the plain derived its name from a colony of Hyrcanians who were settled there by the Achaemenids. According to the modern historian and archaeologist Nicholas Victor Sekunda, the plain was either "confined to the valley of the Pidasos, or it extended in a broad band along the Phrygios from Thyateira to Magnesia-on-Sipylos to the west, and possibly  even as far as Sardis to the southeast". The centre of worship for the Iranian settlers in the Hyrcanian plain was likely the shrine at Hierakome, located almost at the plain's centre. The shrine was probably founded by the first Achaemenid King Cyrus the Great (559–530 BC). Sekunda explains that the Hyrcanian cavalry, which fought at the Battle of Granicus against the invading Macedonians led by Alexander the Great (336–323 BC) have often been seen as colonists from the Hyrcanian plain. However, he adds that it is "much more likely" that the cavalry contingent had actually been sent down  by King Darius III (336–330 BC) to bolster the Achaemenid defenses in western Asia Minor. The name "Hyrcanis" survived into the Hellenistic and Roman-era as a town's name, with its inhabitants being referred to as "Makedones Hyrcanioi". It is suggested that the original Hyrcanian colonists were therefore, at some point, dispossessed or made subject to Macedonian military settlers.