One of the four immortals of Vietnamese folk belief, Thanh Giong is associated with the legend that the Phu Dong boy defeated An, bringing peace to the country. It is said that, after defeating the enemy, he drove to the foot of Mount Soc, took off his horse and rides iron to the sky. It can be said that it is one of the most beautiful and heroic in the treasure of Vietnamese legend. To commemorate his merit, at the foot of Mount Soc, where Giong stopped horse before flying to heaven, people in the area have established temple and annual festival from the 6th to the 8th day of the lunar calendar.