Puyu in Nuzhen means bottomland or waterlogged lowland. The city site oval-shaped, with a perimeter of 2,892 meters. The city wall was built with packed earth and a small defensive town was installed outside the south and north gates. During the south gate excavation in 1975, a number of cultural relics were unearthed, including tiles, pottery ornaments on roof ridge, spokes, iron mirrors, chisels, iron chains and copper coins from the Northern Song Dynasty (960-1127). Among the relics the most important is the tin Puyulu Seal, which provides key evidence proving the city's identity.

The confirmation of Puyulu played an important role in fixing the coordinates of Huoluhuotuan Mouke (Huoluhuotuan in Nuzhen means city in valley; Mouke was an organizational unit of the Jin regime) and the Jin Dynasty (1115-1234) northern border. Hence, it is known that the Chinese territory stretched far to the north of the Outer Hinggan Mountains as early as the Jin Dynasty 700 to 800 years ago.