The Seyhan River (formerly written Seihan, Sihun; ancient name: , 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 Tahtali-Mountains (in Sivas and Kayseri provinces) in the Anti-Taurus Mountains to the Mediterranean Sea via a broad delta. Its main tributaries are Zamanti and Göksu, which unite in Aladag, Adana to form the Seyhan River. The Zamanti River originates from the Uzun Plateau in Pinarbasi, Kayseri and crosses Tomarza, Develi and Yahyali districts in Kayseri.