Here we report the bone collagen carbon and nitrogen isotopic results of humans (n = 33) and animals (n = 58) to reconstruct the dietary practices of an early Qin population dating to the Zhou Dynasty (Late Western–Early Eastern period ca. 700–400 BC) at the Xishan site in Gansu Province, China. The humans have a very large range of δ13C (−23.3‰ to −7.1‰) and δ15N (4.3‰ to 10.9‰) values which reflects extraordinarily diverse diets and included individuals with predominately C3 as well as those with exclusive C4 diets. This wide span of isotopic results produced a subtle linear trend (R2 = 0.62) in the human data, which paralleled the animals across the C3 and C4 environmental gradient. However, the majority of the individuals had a predominately C4 diet based on millet with δ15N results only slightly elevated above the animals, except for the pigs and cattle. This is evidence that many of the animals were likely used for their secondary products, labour or as sacrificial offerings and that pork and beef were the main sources of animal protein for the population. High status individuals had elevated δ15N values (10.2 ± 0.6‰) compared to medium (8.9 ± 0.3‰) and lower status (8.8 ± 0.8‰) individuals, possibly related to increased animal protein in the diet. Differences related to gender were also found with females having elevated δ13C (−11.2 ± 1.9‰) and δ15N (9.4 ± 0.8‰) values compared to the males (δ13C = −14.1 ± 4.2‰; δ15N = 7.9 ± 1.9‰), but these results necessitate caution given the large number of individuals that could not be sexed. The results of this study support the view that the early Qin people were a more sedentary society focused on millet agriculture and animal husbandry, and that they were influenced by the pre‐existing populations of the central Gansu region. Copyright © 2015 John Wiley & Sons, Ltd.