The Liao dynasty acquired the city in 938, when the Later Jin -- one of five short-lived dynasties that ruled northern China after the collapse of the Tang -- ceded the Sixteen Prefectures to the Khitans. The city was then known as Youzhou, a garrison town with a history stretching back centuries but no pretension to imperial grandeur. The Liao renamed it Nanjing and designated it their Youdu Fu, one of five capitals in the empire's multi-capital system. In 1012, it was renamed again to Xijin Fu. Locals also called it Yanjing, a name that persisted long after the Liao fell. The city served as the empire's southern anchor, the point of contact between the nomadic Khitan heartland and the settled agricultural regions to the south.

Liao Nanjing inherited the walled city layout of Tang-era Youzhou, retaining its 26 neighborhood divisions and its market districts in the northern part of the city. The Liao converted the inner city into a walled imperial precinct with four gates. The city's defenses included a moat, likely the waterway once called the Stinking Water River, which ran along what is now Shoushui Hutong. The Fayuan Temple, one of Beijing's oldest surviving Buddhist temples, stood within the Liao city walls and was known during this period as the Minzhong Temple. The Tianning Temple Pagoda, built in 1120, remains one of the few Liao-era structures still standing in modern Beijing, a physical survivor from a city that otherwise exists only in archaeological traces and historical texts.

The fall of Liao Nanjing reads like a spy thriller. When the Jurchen leader Wanyan Aguda founded the Jin dynasty and began dismantling the Liao empire, the northern, central, and eastern capitals fell in rapid succession. For Nanjing, the end came through subterfuge: Aguda sent a subordinate named Zhen Wuchen with fifty soldiers dressed as city residents to infiltrate and open the Yingchunmen gate from within. The Song dynasty, which had failed to capture the city militarily from the Khitans, subsequently managed to purchase it from the Jurchens. Song rule, under the new name Yanshan, proved short-lived. A complex chain of betrayals followed, culminating in the Jurchens' rapid advance on the Song capital of Kaifeng, where the Song emperor was captured in 1127, ending the Northern Song dynasty.

In 1151, the Jin dynasty relocated its capital to Yanjing, renaming it Zhongdu and expanding the city walls to the west, east, and south. Liao Nanjing's northern wall was extended, and gates were renamed. The southern capital of one dynasty became the central capital of another, each expansion overlaying what came before. When the Mongols arrived in the 13th century, Kublai Khan abandoned Zhongdu entirely and built his new capital of Dadu to the northeast. The Liao city, already enclosed within the Jin expansion, vanished beneath layer upon layer of subsequent development. Today, the traces of Liao Nanjing survive in the names of old hutong lanes, in the foundations unearthed during construction projects, and in the Beijing Liao and Jin City Wall Museum, which preserves a section of the water gate that once channeled a river through walls that defined a city no map now shows.