Introduction to grain ash: A large amount of millet grains and grain ash were discovered at the Karuo site, indicating that Tibet had primitive planting industry as early as about 4,000 years ago. According to archaeological research results, millet has been cultivated in my country for more than 7,000 years. The millet grains and grain ash unearthed here are generally consistent with the millet grains and grain ash in the pits of the Banpo site in Xi'an, indicating that the ancestors of Tibet at that time were Agriculture is the main source of livelihood, and hunting or gathering is the main auxiliary means.