Wikipedia
Poipet (officially Paôy Paêt) is a Cambodian boomtown on the Cambodia/ Thailand border, in Ou Chrov district, Banteay Meanchey Province. It is a key crossing point between the two countries, and also extremely popular as a gambling destination as gambling is popular, but illegal in Thailand. There is a strip of casinos and hotels between the Cambodian and Thai passport control counters, enabling Thais to gamble in Cambodia without needing to go through Cambodian immigration. This casino strip area is a 'special zone' that prevents Cambodians from gambling. There is another border on the Cambodian side of this strip area that one needs to pass before being free to travel within the rest of the country.
Poipet is adjacent to the town of Aranya Pratet on the Thai side of the border, the town came into existence only quite recently for the express purpose of border trade, Sisophon had always been the primary urban center in what had been an agricultural area. Poipet's population has increased from 43,366 in the 1998 census to 89,549 in the 2008 census, making it the 4th most populous settlement in Cambodia just ahead of Sihanoukville and larger than its provincial capital Sisophon.