The Beishenjiaqiao cemetery, located in Yanta District, Xi’an City, Shaanxi Province, is a burial ground of the Qin people during the Warring States Period on the Guanzhong Plain. Through the observation and measurement of 63 basically intact skulls unearthed from this cemetery, the following conclusions have been reached: The Beishenjiaqiao group exhibits a combination of mesocranium, high cranial vault, and narrow cranial shape, along with a relatively broad facial type. The maxillary central incisors are mostly spade-shaped, and the canine fossae and nasal root concavities are weakly developed. In comparison with modern Asian Mongoloid groups, it shows the closest affinity with the Fushun group, North China group, and South China group, while maintaining a greater distance from the Mongolian group and Turgus group. Therefore, the inhabitants of Beishenjiaqiao should be classified as the East Asian Mongoloid race. When contrasted with ancient groups in the early pre-Qin period, the Beishenjiaqiao group is closely related to the residents of the “ancient Central Plains type” such as the Yangshao Merged group, Miaodigou group, Taosi group, Chengzi Phase II group, and Dawenkou group, and is also proximate to the residents of the “ancient North China type” like the Miaozigou group. In comparison with ancient groups of the Bronze-early Iron Age, it has a strong connection with the Yin Shang groups such as the Small and Medium Tombs Group 2 and Group C of the Yin ruins, as well as the Qin and Zhou groups including the Wanli group, the Wayaogou group, and the Matengkong group. Considering the long-term and close associations between the residents of Beishenjiaqiao and those in the middle and lower reaches of the Yellow River, especially the closer relationship with the Yin Shang group, and in combination with literature research and other multidisciplinary evidence, it is hypothesized that the Qin people might have been one of the tribes of the Yin Shang group, thereby corroborating the “theory of originating from the east”. Based on the records in the Tsinghua Bamboo Slips “Chronicle”, we can deduce the development trajectory of the Qin people: The Qin might have initially been an eastern ethnic group, either closely affiliated with or even an integral part of the Yin-Shang tribes. After the fall of the Shang Dynasty, they were banished by the Zhou people to the northwest to defend against the Rong tribes. During this period, they coexisted and interacted with the Rong, leading to cultural and genetic exchanges. However, the main body of the Qin people retained numerous cultural traditions and physical characteristics from the Yin-Shang era. In contrast, the Qin people who assimilated into the Gansu-Qinghai region, such as the residents of Maojiaping, perpetuated more of the local physical traits. In the late Western Zhou period, the Qin were rewarded for their efforts in safeguarding the Zhou royal family during its eastward migration and subsequently took control of the Guanzhong region, further enhancing the interaction and integration among the groups along the Yellow River basin.