Vietnam has a large ethnic Chinese community. During the war the ethnic Chinese attended to their businesses and remained largely neutral, so that was not an issue.
They did not feel compelled to leave when Saigon fell.
But there were other problems related to Vietnam's relationship with China. Vietnam has had an interesting relationship with its giant neighbour, going back millennia.
During the French colonial period, the French allowed ethnic Chinese in Vietnam to operate essentially as a state-within-a-state. As Vietnam achieved independence from the French, a series of Vietnamese administrations had to struggle with the problem of bringing the ethnic Chinese into the Vietnamese state. China was no help, particularly after Mao came to power.
Things came to a head around 1978 when Vietnam had a falling out with China over a number of issues, including China's relationship with its diaspora in Vietnam. This falling out led to a war between China and Vietnam beginning in 1979.
In addition to the international tensions, the ethnic Chinese were Vietnam's commercial traders. By 1978 they were forcefully being put out of business by the new communist economy. As a result of these issues, Vietnam's ethnic Chinese felt compelled to leave.
The ethnic Chinese started leaving in large numbers by mid-1978 because that is when the Vietnam government started allowing them to leave. (Robinson, 1998, pp. 27-29).[193]
It grew to an internationally recognized refugee crisis by early 1979. Thus the boat people crisis started.
Background: finding sources for this issue
The Americans tend to dominate any discussion about Vietnam in that period, and the problem of the ethnic Chinese in Vietnam had nothing to do with why the Americans were admitting refugees. Many works mention the issue in passing as if it were insignificant, as it was for the Americans.
US refugee policy was guided by two uniquely American domestic issues: Firstly, the US considered anyone leaving any communist country to be prima facia a refugee.
Secondly, the US expressed an obligation to help anyone who had been involved in any way with the US side in the Vietnam war.
For all other countries and the UNHCR there had to be a reason other than the fall of Saigon, otherwise they would have left the refugees for the Americans to solve.
A secondary problem that is peculiar to Canada is that information about causes has intentionally been hidden by the government. In 2008, Canada decided that it, retroactively, wanted to handle the refugee crisis the same way the US did. Nothing published in Canada or issued by the government since 2008 will mention anything other than "the fall of Saigon" as the cause of the refugee crisis.
The answer for historians studying the issue today is firstly to use sources published before 2008 and secondly to pay special attention to those "passing references" to the Chinese issue. For Canada and the international community it was the issue.
The most authoritative work on the topic is not Canadian. Chang's 1982 work Beijing, Hanoi, and the Overseas Chinese[202] is a must-read for any serious student.
The summary above comes largely from this book.
The most extensive Canadian work (at 10 pages long) is Willmott's 1980 contribution. (Willmott, 1980).[405]
There are other Canadian works from the 1980's that talk about the Vietnamese diaspora in Canada, and some of those discuss the Chinese issue. We will reference those in due course.