Ten kilometres northwest of Jian'ou stands a solitary mountain rising abruptly, covered with lush pines and verdant bamboo, outshining all surrounding peaks. This is Tianhu Mountain.

Tianhu Mountain features steep, winding slopes and twisting paths, its terrain shaped like lotus petals. Upon reaching the summit, one suddenly comes upon a basin: high on all sides, flat and spacious in the centre, dotted with fertile farmland and small lakes—hence the mountain’s name, Tianhu, meaning "Heavenly Lake". The basin is encircled by tall pine and cypress trees, layered green bamboo and dense forest, lending the place a serene, elegant ambience. Within the basin lies a perennial spring whose milky-white water tastes as sweet as fine wine, locally known as Fanjiang Spring, or "Rice Slurry Spring". Folklore claims the spring welled forth where a Buddha spilled rice gruel, a mere folk legend yet a wonder all the same.

Today, Tianhu Mountain houses Yuantong Temple, formerly known as Laofo Nunnery. Records in the Jian'ou County Chronicle tell of a Song-dynasty hermit named Huang Shuixin, given name Miao, who built a dwelling here. Having passed the imperial township examination during the Jingde reign, Huang read widely across countless classics. After the fall of the Song Dynasty, he upheld his integrity and refused to serve the new regime, admiring the lofty moral integrity of Boyi and Shuqi. Zhao Yan, Prefect of Jianzhou in the Song Dynasty, once climbed the mountain and composed the line "Thirty-six vistas grace Heavenly Lake". The mountain boasts thirty-six scenic spots including Twin Rainbow Spring, Void Green Pavilion and Purple Ganoderma Hermitage, all renowned beauty sites. These landmarks were all destroyed amid warfare during the Jianyan reign.

According to the Stele Inscription on the Reconstruction of Yuantong Temple at Tianhu Mountain, written by Weng Henian: "After the temple was ravaged by warfare in the late Xianfeng reign of the Qing Dynasty, only a single ramshackle shelter remained standing. Locals hesitated to launch reconstruction due to the immense scale of the project. A charitable man from Guangzhou named He Kunru resolved to rebuild it wholeheartedly… donating three thousand taels of silver for reconstruction, which was completed in the Bingyin year, the fifteenth year of the Tongzhi reign (1866). The temple halls rose solemn and resplendent, gilded and painted in rich hues. Long corridors led to multi-tiered distant towers; beside the Buddha Hall a shrine for local worthies was erected. Outside the compound wall stood a guesthouse with bright windows and polished tables; small courtyards and ponds were planted with flowers and bamboo. A jade spring supplied water for brewing tea, where curling incense and tea vapours invite visitors to transcend mortal cares."

Yet times change and vicissitudes transform all things. Most devastating was the destruction wrought during the Cultural Revolution: the gate and walls of Yuantong Temple were nearly levelled, all Buddha statues smashed, ritual vessels scattered. Only the bare wooden frame of the Mahavira Hall survived, while all other halls lay in ruins.

In 1978, monastics Jue Ming and Da Jin came to the temple one after another to clear the grounds. The following year, Monk Zeshun assumed the abbotship and launched large-scale restoration work. Over fifteen years, workers renovated the Mahavira Hall and rebuilt three halls: the Heavenly King Hall, Amitabha Hall and Ksitigarbha Hall, alongside two guest lodges, two bone ash pagodas, and a single-eave Thousand-Buddha Bridge—18 metres long and 10 metres wide—plus a hexagonal pavilion at the bridgehead. Today, the halls are filled with lifelike, gilded Buddha statues shining bright. To ease access for sightseers climbing the mountain, the municipal Transportation Bureau partnered with Mafen Village to build a three-kilometre winding mountain highway leading straight to the temple gate.

Since ancient times, crowds thronged the mountain every sixth lunar month to burn incense, and to this day tourists stream here without cease.

Jiang Heng of the Qing Dynasty once wrote: "I once toured Wuyi Mountain and fell in love with the misty, secluded Five Bend Valley with its fantastic rock grottoes, adopting the courtesy name Cloud Recluse in remembrance. Yet the journey was far too long for frequent visits. Should I one day seek a hermitage, it shall lie between Meiyan and Tianhu Mountain—and Tianhu surpasses all others. Thus I named myself the Tianhu Recluse." This passage bears witness to Tianhu Mountain’s timeless allure through the ages