Phra That Si Song Rak is located on the bank of the Barren River. Dan Sai District, Loei Province, was built during the reign of King Chai Chetthathirat in 1560 B.E. and construction was completed in 2106 B.E. Phra That Si Song Rak was built as the evidence of the mutual aid between Ayutthaya (In the reign of King Maha Chakraborty) and Krungsri Sattana Khanhut (now Vientiane, Laos). Both kings reigned in the same period when Burma was powerful, and invaded various territories to expand its power. Therefore, Somdej Phra Maha Chakraborty and Phra Chao Chai Chetthathirat agreed to join forces to fight against Burmese army, and they made an oath not to invade each other's land. And, in order to commemorate their alliance; therefore, they jointly built Phra That Si Song Rak to be the evidence at the middle between Nan River and Mekong River, which is the boundary of the two kingdoms. In addition, within the temple, there is a Buddha image in the posture of a Tibetan Naga prok; the head of the Naga was made of stone, and the Buddha image was made of bronze with the lap width of 21 inches and height of 30 inches Every 15th day of 6th month, residents of Dan Sai District or "Luk Phueng Luk Thian" will join together to organize a royal ceremony; by bringing the bee tree to offer to the relics, it is a sacred tradition that is held annually.