Although the earliest written proof of the word "Phraya Ruang" appeared on the inscription on the base of the Shiva image in Kamphaeng Phet stating its establishment year, 2053, it was assumed that the story of the "Phra Ruang", the legendary hero had been known before and the story was popular after a long time. It was collected in many books, such as Chulayuth Karn Wong, Northern Historical Record, and Statements of the People Living in the City, collected and edited in the late Ayutthaya period until the early Rattanakosin period, as well as in foreign documents such as Cambodia.

The stories of Phra Ruang appearing in these books, despite their many details, the storylines Were quite similar. Phra Ruang was the son of the magician and he was supernatural. Everything he said would become true, called "supernatural words" and he liberates the Thai nation from the invasion or persecution of others.

What is interesting is that in the area that was the center of the Sukhothai kingdom, such as Sukhothai kingdoms, such as Sukhothai and Kamphaeng Phet, there were many stories about Phra Ruang, such as Phra Ruang Tried Using a Weapon, Ban Kuk, Hot Sprig of Phra Ruang, Ban Jorakhe Poon, etc. with were not found in the written evidence, the theme was similar to the main storyline as mentioned above.

The stories of Phra Ruang might have been believed by the people in this area and continued for a long time. They might be used as a description of the phenomenon or objects which cannot be explained by traditional perception, such as hot springs or deep crevices with cliffs along the two sides, and so on. This might also reflect the efforts of the locals to liberate themselves from other cultures. It made these stories so interesting and unique that this area was given the nickname, "Land of Phra Ruang" until the present.