Buddhism is the most influential religion in Vietnam, with about 92 percent of Vietnamese being Buddhists. The number of practicing Buddhists numbers about three million, those who frequently visit Buddhist temples and participate in Buddhist ceremonies number about thirty million, and those living under the influence of Buddhism number in the tens of millions.
In the early centuries, there were a number of small states in the territory of present Vietnam. Buddhism from China influenced the northern state, being for several centuries under the domination of the Chinese empire. The earliest monks were said to have come from China at the end of the second century CE Later, monks from India and Central Asia also arrived by land and sea. The people who also worshipped the native deities practised the Pure Land school of Buddhism. The Chan school of Buddhism, on the other hand, flourished in the monasteries and among Buddhist scholars. Both the rulers and the common people for their literacy respected its monks. Some of them became famous scholars, poets, writers and even royal advisors.
The southern states were exposed to Indian influence from the beginning of the Common Era. Both Mahayana Buddhism and Hinduism were practised then. From the fifteenth century onwards, these southern states were gradually assimilated by the powerful northern state, and as a result the Chinese form of Buddhism also came to influence the south. Finally when Vietnam became unified as a nation, it was the Chinese form of Buddhism that was commonly practised.
At the beginning of the present century, Buddhism in Vietnam underwent some modernisation. Buddhist national organisations were set up and education was emphasised. However, this process was hindered by a continuous period of wars, and came to a virtual stop when the country came under Communist rule.
1) Wikipedia: http://en.wikipedia.org/wiki/Buddhism_in_Vietnam