Sui (589-618) and Tang (618-907) Dynasty Chinese sources depict a world neatly divided between "Chinese" and "barbarians." By focusing on people who crossed the frontier in both directions, this paper argues that these ethnic categories hid a more complex reality. To aid in going beyond the stereotypes that permeate the traditional Chinese histories and government documents, this paper uses under-utilized sources, such as reports of tomb excavations and funerary epitaphs, to present a more nuanced view of the frontier's inhabitants.

    Although the sinicization thesis holds that people normally would not be willing to be parted from "civilized" China, there is evidence of "Chinese" departing to join nomadic groups living to the north. These cases mostly occurred during the transition from Sui to Tang, which was a period of civil instability. As life became precarious and government control abated, people were more likely to leave Chinese controlled areas.

    Movement along the frontier also occurred in the other direction as substantial numbers of "foreigners" came to serve the Tang, especially in the military. A close investigation of so-called barbarians in the army reveals that they were of heterogeneous origins and assimilated to varying degrees into Chinese culture. Despite the fact that the sources give an impression that there was a strong divide between "Chinese" and non-Chinese in the army, ethnic identity was not a consideration for advancement or forming relationships among officers. Loyalty to leaders, rather than ethnic identity, seems to have been the most important bonding element among soldiers.

    In sum, frontier crosser in Sui and Tang times made their moves for pragmatic reasons, not because of attraction to a particular culture or way of life. Shared political and personal loyalties, rather than ethnic identity, were the basis of social bonds.