The Syun is a river in Bashkortostan

Bashkortostan

The Republic of Bashkortostan , also known as Bashkiria is a federal subject of Russia . It is located between the Volga River and the Ural Mountains. Its capital is the city of Ufa...

 and Tatarstan

Tatarstan

The Republic of Tatarstan is a federal subject of Russia located in the Volga Federal District. Its capital is the city of Kazan, which is one of Russia's largest and most prosperous cities. The republic borders with Kirov, Ulyanovsk, Samara, and Orenburg Oblasts, and with the Mari El, Udmurt,...

, Russian Federation

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, a left-bank tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Belaya River (Kama basin). Its length is 209 km (74 of them in Tatarstan) and its drainage basin

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

is 4,500 km².
Major tributaries in Tatarstan are Kalmiya, Sikiya, Terpelya, Bezyada, and Sharan in Bashkortostan. The maximal water discharge is 655 m³/s (1979), the maximal mineralization 500-1000 mg/l. Average sediment in mouth per year is 120 mm. Drainage is regulated. Since 1978 it is protected as natural monument of Tatarstan.