Beneath the grass of Deyuan Mountain, a layer of ancient charcoal dates the first human presence here to the year 610. Long before the rise of empires, the Wangqian tribe warmed themselves by these fires, leaving behind carbonized wood that still smudges the fingers of modern archaeologists. By 738, this high ground became Dengchuan City, the capital of the Dengdan Zhao. Its end came in a flash of pine smoke and betrayal. When the Nanzhao king Piluoge burned the rival leaders alive in a wooden pavilion, Lady Cishan searched the ashes. She identified her husband’s charred bones by the cold iron bracelets she had fastened to his wrists. She refused to surrender her city or her freedom to the conqueror. She barricaded the gates and died, leaving her name, meaning 'source of virtue,' to the fortress.

The ruins form an irregular oval covering 52,700 square meters. Builders shaped the city to the mountain, raising gritty rammed earth walls up to 3.8 meters high and seven meters thick. On the eastern ramparts, shallow ash piles mark where sentries and laborers lit small fires to survive the freezing mountain nights. To the north, defenders carved two massive dry moats into the bedrock, each ten meters wide and seven meters deep, to stop northern invaders. Inside, the ground rises across four distinct terraces. Excavations on these levels revealed the physical debris of daily survival: ceramic water pipes, square green bricks, and roof tiles bearing the rough, hand-pressed patterns of Tang dynasty artisans.

The Nanzhao kings Geluofeng and Yimouxun reinforced these walls against the Tibetan Empire. Eventually, the city fell silent. It woke briefly in the seventeenth century when natural disasters forced the local government to retreat to this high sanctuary for a decade. Today, the highest terrace holds a rebuilt shrine to Lady Cishan. Every summer, local women crush wild balsam flowers to stain their fingernails red, a quiet ritual honoring the blood she spilled while digging through the ashes of the pine pavilion.