According to the "Khmer Great Man" document, the name "Kep" is derived from the French word "Cap", which the French used to Called when the French put the yoke of control in Cambodia from 1863 to 1953. The word "Cap" means in Khmer "Chroy" in line with the geographical location of the Kep area is sloping or sloping into the sea. That is why it is called Kep or "Cap" in French, meaning "the city of Chroy". Land flows into the sea, and this word is constantly called "Kep" forever.

According to legend, in the glorious era of Mohanakor, there was a Laotian king named "Sakor Reach" who was educated Martial arts are very strong and know the magic of great tranquility. One day, when he saw a beautiful white horse, he wished to use great magic on the commander. The Khmer, who owned the white horse, slept for a long time and stole the horse and fled from the area. Angkor (in the territory of present-day Siem Reap) with both wives and soldiers.

Later, the resting captain regained consciousness and lost his beloved horse, and led his troops to search for his horse. Traces of horses to the southwestern part of the country (present-day Kep Province) and saw their horses with "Sakor Reach". At that time, there was a fierce battle with each other, and "Sakor Reach" at that time did not win the battle, the Khmer army chief withdrew He retreated on the back of the horse to escape the danger, but the horse became furious, causing him to fall on his back. The horse was injured in the fall. Seeing such a disaster, "Sakor Reach" tried to jump on the back of another of his horses and quickly escaped. Disappear with the troops.

Later, the Lao king ran from place to place until he set up camp on the top of the mountain. One (Phnom Laos today), located to the east of the site of the fall, more than 4 kilometers. Soon the news of the camp reached the Khmer commander, and the Khmer commander sent troops to capture the Lao king "Sakor". The king of Laos also took his wife and soldiers to hide in another mountain in the west. About 1 km. From this mountain, "Sakor Reach" and the soldiers swam across the sea to camp on an island more than 4 kilometers away. From the shores of the mainland.

Later, the Khmer army attacked the island again until all the Laotian troops on the island were disbanded. . After this, when the army broke away, "Sakor Reach" ran alone around the mountain. The other is located more than 10 kilometers north of Kep Sesh.

In relation to the history of such legends, the mountain where the Lao king camped was called "Phnom Lao". The Laotian king hid himself "Phnom Puon" but later called "Phnom Poun" and the mountain where the Laotian king Runs around, it is called "Phnom Sarasar" to this day.

The island where the "Sakor Reach" army camped was called "Koh Romsay" but later called "Koh Tonsay".

As for the location where Kep Ses fell, it was called "Kep Ses Village", but later because the name was too long, it was called "Short". Kep village "until the city was named" Kep city ".
After 1979, Kep province was just a commune called "Kep commune" in Kampot district, Kampot province. On August 11, 1992, the National Assembly of the State of Cambodia passed a law on the re-establishment of Kep City. Later, it was renamed "Kep Province" on December 22, 2008 and operates until today.