The Chi River (Template:Lang-thai-lao) is the longest river in Laos and Thailand at 765 km, although it carries less water than the second longest river, the Mun. The River Thames in London River running into Harrietville Trout Farm A river is a large natural waterway. ... The Mun River (Thai แม่น้ำมูล) is a tributary of the Mekong river. ...

The river rises in the Phetchabun mountains, then runs east through the central Isan provinces of Chaiyaphum, Khon Kaen and Maha Sarakham, before turning south in Roi Et and running through Yasothon to meet the Mun in Kanthararom district of Sisaket Province. The river carries approximately 9,300 cubic kilometres of water per annum. Western chain in morning fog with the Pa Sok valley in front The Phetchabun mountains are a mountain range in Thailand. ... Chaiyaphum (Thai ชัยภูมิ) is one of the north-eastern provinces (changwat) of Thailand. ... Khon Kaen (Thai ขอนแก่น) is the second-largest of the north-eastern provinces (changwat) of Thailand. ... Maha Sarakham (Thai มหาสารคาม) is one of the provinces (changwat) of Thailand, located in the North-East of Thailand. ... Roi Et (Thai ร้อยเอ็ด) is one of the provinces (changwat) of Thailand, located in the North-East of Thailand. ... Yasothon (Thai ยโสธร) is one of the provinces (changwat) of Thailand, located in the North-East of Thailand. ... Si Sa Ket (Thai ศรีสะเกษ) is one of the north-eastern provinces (changwat) of Thailand. ...