It is the earliest known observatory in the world with a mature calendar system, according to researcher He.

Then there is the free-standing, ceremonial gate tower that was discovered at the site in 2015.

The structure resembles the entrance of the Forbidden City in Beijing.

Nevertheless, many experts associated with the project say more studies are necessary before coming to conclusions about the site.

Old history textbooks say the first Chinese dynasty belonged to Xia, who ruled from the 21st century BC, and may have descended from Yao's successors.

However, there is no archaeological evidence to support the theory yet.

Though similarities have been noticed between "character-like scripts" found at the site and "oracle-bone scripts" of later times, the formation process remains unclear, which calls for comprehensive and interdisciplinary research, experts say.

At the moment, Gao and his team are working at the Palace No 2 site that is located some 150 meters away from Palace No 1.

"From what we know so far, Palace No 2 was used for 100 years," Gao says.

Both palaces were built during the early stages of Taosi culture.

"We will study the other palaces one after another for the big picture," he adds.