Kayes is a city in western Mali on the Sénégal River with a population of 127,368 at the 2009 census. Kayes is the capital of the administrative region of the same name. The name "Kayes" comes from the Soninke word "karré", which describes a low humid place that floods in rainy season. The city is located 420 kilometres (260 mi) northwest of the capital Bamako.

The Senegal River is a 1086-kilometre-long (675 mi) river in West Africa; much of its length marks part of the border between Senegal and Mauritania. It has a drainage basin of 270000 km2, a mean flow of 680 m3/s (24,000 cu ft/s), and an annual discharge of 21.5 km3 (5.2 cu mi). Important tributaries are the Falémé River, Karakoro River, and the Gorgol River. The river divides into two branches once it passes Kaédi The left branch, called the Doué, runs parallel to the main river to the north. After 200 km (120 mi) the two branches rejoin a few kilometers downstream of Podor.