For the most part the province was part of Siam (Thailand) until 1907 when it was taken over by the French Indochinese Colonial authorities. Since then it has largely been an integral part of Cambodia, although it was briefly controlled by Thailand form 1941-45.
Since then its history has largely been one of war, firstly against the French and then by the Khmer Rouge against the central government.
Its association with the Reds would continue through until 1998 when it was the capital of the last Khmer Rouge state, as well as where Pol Pot died. Since then there has been some investment as the area has reintegrated into Cambodia, as well as intense interest in Dark Tourism and Khmer Rouge tourism within the area.