Kızılırmak River  The Kızılırmak (, Turkish for "Red River"), also known as the Halys River () (N. Marr explained its name by the Laz word meaning "river") is the longest river entirely within Turkey. It is a source of hydroelectric power and is not used for navigation. The Kızılırmak flows for a total of , rising in Eastern Anatolia around , flowing first to the west and southwest until , then forming a wide arch, the "Halys bend", flowing first to the west, then to the northwest, passing to the northeast of Lake Tuz, then to the north and northeast, where it is joined by its major tributary, the Delice River (also known by its Greek name Cappadox) at , and after zigzagging to the northwest to the confluence with the Devrez River at , and back to the northeast, joining the Gökırmak before finally flowing through its delta into the Black Sea at . Dams on the river include the Boyabat, Altınkaya and Derbent. The Hittites called it the Maraššantiya. It formed the western boundary of Hatti, the core land of the Hittite empire. Until the Roman conquest of Anatolia the Halys River, later called by Turkish conquerors the "Kızılırmak", served as a natural political boundary in central Asia Minor, first between the kingdom of Lydia and the Persian Empire, and later between the Pontic Kingdom and the Kingdom of Cappadocia. In the 1st century AD Vespasian combined several provinces, including Cappadocia, to create one large province; its eastern boundary was marked by the Euphrates River. This province once again splintered during Trajans reign—the newly created province of Cappadocia, bounded by the Euphrates to the East, included Pontus and Lesser Armenia. The Halys River remained an interior river and never regained its significance as a political border. In the 130s a governor of Cappadocia wrote: "long ago the Halys River was the boundary between the kingdom of Croesus and the Persian Empire; now it flows under Roman dominion." As the site of the Battle of Halys or Battle of the Eclipse on May 28, 585 BC, it was the border between Lydia to the west and Media to the east until Croesus of Lydia crossed it to attack Cyrus the Great in 547 BC.