Pailin was originally a small forest zone full of animal and several precious stones. Pailin is the transform word from the original Pan Len referred by a tale about around the 18th or 19th century, there were a group of hunters who chased the wild animals farther and farther until they reached the present-day Pailin where, then, was of jungles of high trees and some fields by the canal which was called small river such as Tong small river. The hunters saw otters that were swimming and they ran away when they saw people. Then, the hunters went to see the place where the otters played together. They saw small bright rocks and everybody took a rock to show their friends and their relatives in their home land. Arriving in the home land, there were residents (it was said they were Kula people in Chanthaburi Province Siam) knew that the rocks were valuable so they took and broke the rocks to polish into gems with good purity. That was why they went to buy gems from the hunters. The hunters knew that it was way of earning a living, they often tried to go to take the rocks from the old place. At that time, Pailin began to faced as the business place.
The frequent going and coming from that place made them call Phee Leng due to the playing of the otters that they saw at the first time. But the residents in Siam pronounced Phee as Phai and Leng as Len or Lin with their Siamese sound as Pea Lea . During the control of France of that area, it was written in Latin with the sound and morphology of the words as Phailin. Later the word was shortened as Pailin by omitting " H "aim of a difficult pronunciation.
In the late 1970s, Pailin was a prosperous town stemming from the extensive gem deposits in the surrounding countryside. Because of its resources, it was one of the first cities invaded by the Khmer Rouge when they began their major offensive against the national government. The city offered no resistance and the Khmer Rouge soldiers were greeted as
