Perched atop Siding Peak, the main summit of Bagong Mountain, once stood the Bixia Yuanjun Temple. Since it sits on Siding Peak, it is also widely known as Siding Nainai Temple (Grandma Siding Temple), one of the historic landmarks of Bagong Mountain. The temple was originally enshrined with statues of the goddess Bixia Yuanjun, hence its formal name. Locals in Shouzhou and Fengtai mostly call the deity Grandma Siding, so far more people know it as Siding Nainai Temple rather than Bixia Yuanjun Temple. The Shouzhou Chronicle compiled by Li Yonglu during the Jiajing reign of the Ming Dynasty referred to it as the East Sacred Shrine, while the Fengtai County Records edited by Li Shiyuan in the Jiaqing reign of the Qing Dynasty named it Yuanjun Temple.

The exact construction date of Yuanjun Temple (Siding Nainai Temple) remains unrecorded. According to the Fengtai County Records, a local resident named Wu Fangchun donated funds to renovate the temple during the Jiaqing period. The records note that the auxiliary palace of Bixia Yuanjun on North Hill was built in the eighth month of the 19th year of Jiaqing. The stone inscription recording the renovation reads roughly: “Bixia Yuanjun, divine consort of the Eastern Sacred Mount Tai, has a palace erected upon this mountain. This sacred hall has stood for many years, yet its beams and pillars have decayed. A gentleman surnamed Li from Wujin managed the construction of this auxiliary palace over five years. During this time, harvests were abundant year after year, and no plagues befell the people. Local villager Wu Fangchun contributed a sum of private money, selected an auspicious day, and hired labourers to restore the shrine. This stone tablet is carved to record the event.”