Atrai River one of the sacred rivers mentioned in the mahabharata. Its ancient name was Atrei. It originates about 10 km northeast of Shiliguri town of west bengal (India). Then it flows west of the jamuna. It is the westernmost distributary of the brahmaputra. It changes its name from karatoya to Atrai near khansama upazila of dinajpur district. It again enters Bangladesh through naogaon district. The channel bifurcates northwest of chirirbandar and unites again southwest of it. The western part is called the Gabura and the eastern part the Kankra. It flows through the eastern part of Dinajpur town and enters West Dinajpur of West Bengal after passing through Bhusir Bandar and Samjia Ghat.
The river then flows due south to manda upazila dividing the east-central and west-central parts of the barind tract. It flows south and turns southeast, then flows through chalan beel and meets the hurasagar river. It meets Jamuna near Baghabari through Hurasagar. The Atrai has several tributaries of which the punarbhaba is the best known. Fakirni and Baral on the rightbank and the Karatoya on the leftbank also deserve mention. In the greater Rajshahi-Pabna region its tributaries are the Tulsiganga, Nandakua, Baranai and baral. The length of the river is about 380 km. [Mesbah-us-Saleheen]
See maps in BRAHMAPUTRA-JAMUNA RIVER SYSTEM.