Han says the site is a high-level settlement which may have functioned like a capital in the past.

"The core area is located at the center of the whole site, the 'palace' area is in the center of the core area, and the main structure, F1, is in the center of the 'palace' area with a central axis. The strict layout, which is very close to those in capitals and palaces of the later dynasties, has never been found at other sites contemporaneous with Nanzuo," says Han.

With a southern exposure, the main building, F1, has a total area of more than 800 square meters, and the internal floor space is more than 630 sq m. It is divided into an antechamber and a rear hall, with three doors.

"Architecture in later dynasties often shows such a layout as well. The middle door is believed to be holy and not one that is normally used, and the two on the sides are subordinate," says Han.

He also mentions that architecture found at the Dadiwan site, a prehistoric site dating back 4,800 to 8,000 years in Gansu, has such a design, too, although the structure is much smaller in size than that of Nanzuo.