Pailin (ខេត្តប៉ៃលិន) is best known for its gem mines (now pretty much exhausted), a surfeit of land mines and for being a refuge for Khmer Rouge pensioners.

During the civil war, the Pailin area’s gem and timber resources – sold on international markets with help from Thai army generals – served as the economic crutch that kept the Khmer Rouge war machine hobbling along. In the mid-1990s, it was a staging area for regular dry-season offensives that overran government positions as far east as Phnom Sampeau.

In 1996, the Khmer Rouge supremo in these parts, Ieng Sary – or Brother Number Three during the Democratic Kampuchea regime – defected to the government side with 5000 heavily armed troops. His reward was amnesty and free rein in Krong Pailin, a mini-province carved out of Battambang Province to serve as a Khmer Rouge fiefdom. Only in 2007 were Ieng and his wife arrested for war crimes and crimes against humanity. He died in March 2013, well before the completion of the trial.

It wasn't until 2014 that Y Chhien, who once served as the chief bodyguard for Pol Pot, stepped down as governor of the Pailin province. Ieng Vuth, the son of Ieng Sary, stayed on as deputy governor.