TISTA, a river of northern India, which rises on the edge of the Tibetan plateau, and flows through the mountain gorges of Sikkim and Darjeeling, till it spills itself over the plain of Eastern Bengal. In the 18th century its course was due south to join the Ganges; but in 1787 great floods diverted the stream towards the south-east, and it now enters the Brahmaputra, the whole district of Rangpur being scored by various interlacing channels. Its total length in British territory is about 170 m.