Chi River

Template:Geobox The Chi River (Template:Lang-th) is the longest river in Thailand; it extends 765 km, but carries less water than the second longest river, the Mun. In the Isan dialect of this region, and also in the adjacent language Lao, the name of the river is actually pronounced "Nam See" (sii) but the transliteration Chi reflects Bangkok-Thai.

The river rises in the Phetchabun mountains, then runs east through the central Isan provinces of Chaiyaphum, Khon Kaen and Maha Sarakham, and turns south in Roi Et, 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. It is riddled with leeches.

The river was an 18th century migration route for the expansion of the ethnic Lao people over the Isan plateau (a history recorded and remembered, largely in terms of the struggle to expand wet-rice cultivation in the river valley), who are now regarded as a separate ethnos from the Lao to the North or the central Thai to the South-West.