Piyain River a trans-boundary river of India and Bangladesh. It is a tributary of the Surma river, which is originates from the Umngot of Meghalaya. The river enters Bangladesh through Sylhet district.

The length of the river is 145 km. Piyain river has emerged from the river om or Umagat river or Assam.

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  Piyain River at Zero Point Jaflong
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  Piyain River at Chhatak Upazila
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  Piyain River. The picture was taken on the way to Bisnakandi

• Piyain River at Banglapedia

24°46′N 91°06′E / 24.767°N 91.100°E / 24.767; 91.100