Flax use in ancient China: Archaeobotany evidence from the Northwest China

Flax ( Linum usitatissimum ), a versatile annual herbaceous plant, can be categorized into three types based on phenotypic traits: oil, fiber, and oil-fiber varieties. With a domestication history spanning nearly 9000 years, flax remains one of the most significant fiber and oil crops in human history. Given the limited archaeological discoveries of flax remains in China, recent findings at two sites provide valuable insights into its historical utilization. At the Tangchaodun Ancient City site (seventh-14th centuries AD) in the northeast Qitai County, Xinjiang, 69 carbonized flax seeds were discovered. AMS 14 C dating places these seeds in the late 10th century AD. This is the largest number of flax seeds unearthed from China to date. Additionally, 13 desiccated flax seeds from nine silk “grain bags” were excavated in the tomb of King Murong Zhi of the Tuyuhun Kingdom (AD 691) from the Chashancun cemetery in Wuwei, Gansu Province, marking it the earliest credible flax remains discovered in China. Principal component analysis (PCA) of 18 modern flax varieties (oil, fiber, and oil-fiber types) indicates that these ancient seeds share morphological similarities with fiber and oil-fiber varieties. While the precise function of flax at Tangchaodun remains uncertain, it may have been used for fiber production or religious purposes. In contrast, flax seeds in the tomb of King Murong Zhi, co-discovered alongside other crops such as hemp, millet, broomcorn millet, muskmelon, buckwheat, hulled barley, and barley, were likely used primarily for fiber and/or oil-fiber flax, consistent with records from the records documented in Wooden Slips of the Han Dynasty. This study provides a new understanding of the role of flax in the economic and social life in ancient China.