Fermented beverages have long been a part of social and religious rituals. Now, researchers have identified a beer-making toolkit at an archaeological site in northern China with a 5,000-year-old recipe for beer.

Ancient pottery vessels, dating to 3400-2900 BC, contained a fermented mixture of barley, broomcorn millets, and other starchy plants. It is the earliest direct evidence of beer brewing in ancient China, the authors say.

“Beer was probably an important part of ritual feasting in ancient China,” says study author Jiajing Wang of Stanford University. “So it’s possible that this finding of beer is associated with increased social complexity and changing events of the time.” The discovery is described today in PNAS.

Technicians excavated the artifacts in 2004-2006 from two pits at the Mijiaya archaeological site in northern China. The pits also contained stoves, likely used to heat the grains for mashing. Stanford professor Li Liu became aware of the pottery shards while reviewing a report from the excavation, and immediately noticed a vessel shaped like a funnel, which would have been used to pour a newly made beverage into a storage container.

Wang and Liu traveled to China and retrieved samples from the artifacts, scraping a yellowish residue from the inside of each vessel. They then worked with Terry Ball at Brigham Young University and two research institutes in China to analyze the samples. They identified three lines of evidence suggesting the vessels were indeed used to make a fermented beverage.

First, the shapes of the vessels correspond to all three steps of the beer-making process: brewing, filtration, and storage. Second, microscopic analysis of the residual grains revealed a damage pattern matching how grains are pitted and distorted during the brewing process.

Third, whole grains are a requirement for brewing beer, and the scientists observed the presence of husks from barley, broomcorn millet, and Job’s tears, a grain native to Southeast Asia.

“It makes a very convincing case that this was a beer-making facility,” says Patrick McGovern, scientific director of the Biomolecular Archaeology Project at the University of Pennsylvania Museum in Philadelphia, who was not involved in the study.

In 2004, McGovern and colleagues published evidence of the earliest known fermented beverage in China, which they found at the 9,000-year-old early Neolithic site of Jiahu in the Yellow River valley. The fermented beverage was made of rice, honey, hawthorn tree fruit, and wild grapes.

The date of the Mijiaya vessels coincides with evidence of beer-making in Iran, Egypt, and Armenia around the same time—all dated from about 3500-3000 B.C., says McGovern, implying that was a time when knowledge about fermented beverages spread around the globe. The finding also suggests that barley was introduced to the Central Plain of China first for beer brewing, and only later did it became a staple as a subsistence crop, the authors suggest.

Overall, the new discovery “starts to fill in the gap between 7000 B.C. to around the Shang dynasty in 1500 B.C., when one starts to see more specialized fermented beverages,” says McGovern. Wang hopes to fill in more of that gap by seeking and testing pottery from other sites around China, to find out when and how societies around the country began making beer.