From a recent email:
Like the Chinese, Japanese and Koreans, Vietnamese consider their compatriots as not just belonging to the same race, but family, and in the most literal sense, too, for they call other Vietnamese, “đồng bào” [“same womb”], which is derived from the Chinese, 同胞. This notion is obviously more myth than science, for the Vietnamese nation has absorbed plenty of foreign blood through the millennia, via the usual channels of conquest and immigration. Without the bonding concept of đồng bào, however, Vietnam would have disappeared eons ago.
Vietnamese citizenship, then, is much more than a legality, but established through the age-old recognition that people who appear similar and, even more importantly, speak the same language naturally belong together. Often, they must also fight together to resist being swallowed up or destroyed by another race. Race consciousness is at the heart of racial survival. (Source)