The Third Month Street Fair is the grandest show of the year for the Bais. Held from the 15th day to the 21st day of the third lunar month every year at the foot of the Mount Diancang Shan,west to the ancient city of Dali, the Bais are holding the festival mainly pray for a good harvest.The Third Month Street is also named the Market of Guanyin, literally the Goddess of Mercy.

 Legend has it that back in the period of Nanzhao State (938-1253), the Goddess of Mercy came to Dali to speak on Buddhism on the 15th of the third lunar month, and then the Third Month Street became a temple fair for loyal believers to pay homage. As time went, for Dali's strategic location, the city became a prosperous trade market in the region and a grand festival for the local people.