Archaeologists in northwest China have identified 3.74 liters of grain-based alcohol dating back around 2,300 years, offering rare evidence of brewing techniques used by the Qin people during the Warring States Period (475 BC-221 BC).

The liquid was recovered from a bronze vessel unearthed at the Shanjiabao cemetery in Guyuan, northwest China's Ningxia Hui Autonomous Region, the regional Department of Culture and Tourism said on July 28.

The Shanjiabao cemetery is located in Yuanzhou District of Guyuan, close to a section of the Qin Great Wall. Archaeologists have excavated 183 tombs at the site, all dating to the Warring States Period.

The ancient liquid was found inside a bronze vessel known as a suantouhu, or garlic-bulb-shaped flask, a distinctive object associated with Qin culture. Researchers found that the vessel had been sealed using two protective layers: a textile lining on the inside and an organic mud coating on the outside. The sealing system helped prevent contamination and significantly reduced evaporation, allowing much of the liquid to survive for more than two millennia.

The discovery fills a gap in the archaeological record of alcohol production in Ningxia and provides new physical evidence for the long history of grain brewing in China. Researchers said the discovery may also contribute to the study of early agriculture, food and drinking customs, and the development of handicraft technologies before China's imperial unification.