The Seyhan River (formerly written Seihan, Sihun; ancient name: Σάρος, Sarus) is the longest river in Turkey that flows into the Mediterranean Sea. The river is 560 km and flows southwest from its headwaters in the Tahtalı-Mountains (in Sivas and Kayseri provinces) in the Anti-Taurus Mountains to the Mediterranean Sea via a broad delta. Its main tributaries are Zamantı and Göksu, which unite in Aladağ, Adana to form the Seyhan River. The Zamantı River originates from the Uzun Plateau in Pınarbaşı, Kayseri and crosses Tomarza, Develi and Yahyalı districts in Kayseri.