20 Riels Khmer Rouge

The Khmer Rouge never operated a conventional monetary system during its period of government — in fact, currency was abolished entirely after April 1975, and the National Bank of Cambodia was physically demolished. These notes, designated by collectors under the "R" prefix to separate them from legitimate Cambodian issues, were produced not for actual circulation but as a propaganda instrument during the movement's long guerrilla phase after its 1979 ouster. The Khmer Rouge controlled pockets of western Cambodia through the early 1990s, and these notes belong to that twilight period of insurgency rather than to any functioning economy.

No credible evidence suggests they circulated in any meaningful commercial sense.