Koei Chai

Koei Chai (Thai: เกยไชย, pronounced [kɤ̄ːj t͡ɕʰāj]) is a tambon (sub-district) of Chum Saeng District, Nakhon Sawan Province, upper central Thailand.

Koei Chai dates back to Ayutthaya period, at that time it was called "Koei Sai" (เกยทราย, literally: beached sand), which at the confluence of the Nan and Yom Rivers was the place where the hydraulic lime tanker falls in the reign of King Suriyenthrathibodi (Sanphet VIII), also known as Tiger King.

At present, it is the location of Wat Koei Chai Neua, an ancient temple with a pagoda that contained the relics of Lord Buddha.

In the reign of King Chulalongkorn (Rama V) in Rattanakosin period, this district was also famous for its large man-eating crocodile, named "Ai Dang Koei Chai" (ไอ้ด่างเกยไชย), it was said that the body was so large that it can across from one side to the opposite side of Nan River.

According to a short note, only two lines of Prince Damrong stated that its skull was very large and was preserved here, but at that time it had already been sold to a foreigner in Bangkok.