The 23 wooden strips found inside a tomb are believed to be an ancient celestial calendar (Credit: Chongqing Cultural Relics and Archaeology Research Institute)

Archeologists in China have unearthed what they believe is an ancient "celestial calendar." The 23 rectangular wooden pieces were found inside a 2,200-year-old tomb in China's Wulong District. They are etched with Chinese characters connected to an astronomical calendar known as Tiangan Dizhi. It was established during the Shang dynasty, which ruled from 1600 BC to about 1050 BC. This is the first time written slips linked to the ancient calendar have been found in a tomb.

"The wooden slips with calendric notations are significant as the first and only known example of that kind of inscription on that kind of object," Ed Krupp, Director of Griffith Observatory in Los Angeles, told Live Science.

The calendar was found in a tomb dating back 2,200 years (Credit: Chongqing Cultural Relics and Archaeology Research Institute)

The team, led by Huang Wei at the Chongqing Institute of Cultural Relics and Archaeology, revealed their discovery on December 5, 2023. The scientists say circular perforations on the edges of the bamboo strips indicate all 23 were once tied and used together. However, they do not know how the calendar, which was based on a 60-year cycle, worked. They theorize that one piece represented the then-current year, while the rest were used to highlight other years.

The tomb contained many expensive artifacts (Credit: Chongqing Cultural Relics and Archaeology Research Institute)

Based on the skeleton's condition, Wei and his team determined that the occupant was a strong, middle-aged male. The copper spears, bows and arrows, and other weapons found alongside suggest he may have been good at martial arts. The tomb also contained numerous high-quality objects, including copper and bronze pots. This has led Krupp to suspect its owner was a person of high status.

"The artifacts interred with the deceased are numerous and very, very fine," he said. "This is rich, expensive material."