Kalimantan is the Indonesian part of the island of Borneo. It occupies the central and southern regions of the island. It is divided into four provinces, Kalimantan Barat (west, with capital Pontianak), Kalimantan Tengah (south, with capital Palangkaraya), Kalimantan Timur (northeast, with capital Samarinda), and Kalimantan Selatan (southeast, with capital Banjarmasin).

There is a war in this region between the indigenous Dayaks and the Madurese immigrants, who were moved here in a government "transmigration" programme that operated, in various forms, from 1905 until 2001. The Dayak fighters are known for their ferocious tactics, such as the beheading and mutilation of their victims.

See also Kalimantaan, a novel by C. S. Godshalk, which is set in Borneo.