Abstract: For long time, it has been generally believed that the decrease of millet agriculture during the Xiaoheyan Culture Period led to cultural declination compared to that during the Hongshan Culture Period. The carbon and nitrogen isotope analysis of human bones from the Jiangjialiang site, Yangyuan, Hebei, dated to early stage of Xiaoheyan Culture, was undertaken in this paper. The averageδ13C and δ15N values of human collagen are -7.0±0.3‰(n=25) and 8.8±0.4‰(n=25) respectively, suggesting that millet-based foods, including millets and milletsconsuming animals, were dominant in human diets. The difference of δ13C values between the genders indicates that the females relied on more gathering. It is notable to see that millet agriculture during the early Xiaoheyan Period was more developed than that during the Hongshan Culture Period. Thus, the real reason to account for the cultural decline of Xiaoheyan Culture still needs to be considered.

Key words: Southern and Northern Yanshan area; Xiaoheyan Culture; C and N stable isotopes; Jiangjialiang site