Once mistaken for the Great Wall of China, archeologists have unearthed an ancient city complete with a 70-meter (230-foot) pyramid, decapitated heads, and a bounty of precious gems.

The 4,300-year-old stone city is now named Shimao, although its ancient name is unknown. At 400 hectares, the city was not only the largest walled settlement of its time, it was also among the largest urban settlement in the world – and its discovery challenges commonly held beliefs about how Chinese civilization emerged.

Shimao is found in a region often been described in Chinese histories as a home to "barbarians". While little is known about the ancient city, its grandeur and intricacy suggest it was once politically and economically important in the region. The buildings were quarried from nearby sandstone whose extraction, transportation, and use were labor-intensive and sophisticated.

Take the pyramid palace built in the center of the town, for starters. Built around 2300 BC, the 11-story structure was reinforced with stone buttresses and defensive walls. Found in the walls of the pyramid and in nearly every stone structure are jade insets, tools, and other decorations.

Walk outside and you’ll find yourself in a large, open plaza that was probably used for ritual or political purposes. The pyramid is visible from everywhere within the settlement, from the smaller homes to the storage and garbage deposits. The palace likely served as a symbol of power for the city’s elites, as well as a space for artisanal or industrial craft production. 

"In comparison with the palaces atop the pyramid, constructions beyond the pyramid complex were much more humble, both in terms of size and building techniques," wrote the researchers. "These structures were in the form of either cave dwellings or subterranean/semi-subterranean dwellings."

Life here wasn’t quite idyllic as the palace makes it appear. Six pits containing decapitated human heads indicates that human sacrifice occurred here on a “massive scale”. Morphological analyses of the remains suggest the victims could have been captives from nearby warring groups – a claim reinforced by the fortified walls strategically placed around the city to keep people out.

“The jade objects and human sacrifice may have imbued the very walls of Shimao with ritual and religious potency, amplifying its significance as a monumental center, enhancing the protective efficacy of the walls and making this a place of power in every sense,” wrote the authors in their study published in Antiquity. 

The team speculates that Shimao flourished over such a large region for around 500 years and could have encompassed more than 4,000 settlements.

[H/T: Live Science]