In 264 AD, the Chinese Wu (Ngô) Dynasty divided the former province of Jiaozhi (Giao Chỉ) into the
provinces of Guangzhou (today’s: Guangxi and Guangdong) and Jiaozhou (Giao Châu, today’s Northern
and Northern Central Vietnam). Basically, today’s national land border between the PRC and the SRV
is a result of this provincial division. However, the separation of the two provinces did not prevent
border conflicts after the former Giao Chỉ or Annam proclaimed itself independent in 939 AD. Peoples
of the same origin (today: ethnic minorities who live in Northern Vietnam and Southern China) settled
on both sides of the mountainous border and entertained all kinds of relations, so that incursions and
encroachments from the on or the other side were a very common phenomenon, especially when one of
the two countries had a period of weak central or regional government.
The example of the Châu of Bảo Lạc (Cao Bằng) shows, how a territory, that was mentioned as a conflict
spot for the first time in 1084, got lost to Vietnam in 1467 and returned to it in 1725, after 258 years of
protracted negotiations involving two Vietnamese (Lê and Mạc) and two Chinese dynasties (Ming and
Qing). The complex mechanism of border security, human control and conflict settlement was
inextricably linked to both Chinese and Vietnamese central and regional interior politics. In a period,
when China was united and strong, and the much smaller neighbour, the Vietnamese vessal state,
behaved in a way that fully acknowleged China’s self-assumed political and spiritual hegemony, a
practical solution that satisfied both sides, in fact the Southern partner more than the Northern, could be
found. However, when the French wanted to reach a general settlement with China after the inconclusive
border war (1885), Southern Chinese governors were quick to seize the opportunity and demanded the
“lost territory” back again. Bảo Lạc was divided, and the larger part has become Chinese since then.