upper Burma where its victory over, and destruction of, the Pyu
kingdom only opened the way for the Burmans to become the domi-
nant ethnic group, and to establish the kingdom of Pagan.
By the end of the tenth century, an independent Vietnam and
independent Nanzhao seemed to define the limits of Chinese expan-
sion into Southeast Asia. Both had been subjected not only to
extensive sinicisation, but also to substantial Chinese settlement.
Many of these settlers had intermarried with the local population,
however, and owed little allegiance to their homeland. Both Vietnam
and Nanzhao accepted tributary status in their dealings with China, a
relationship that under the Song—when Nanzhao had contracted to
form the kingdom of Dali—settled into comfortable mutual non-
aggression.
There were important differences between Dali and Vietnam,
however, that go some way towards explaining why only the latter
retained its independence in the face of Mongol expansionism. For
one thing, Vietnam was administered on the Chinese model, while
Dali was a looser, Southeast Asian mandala. Also in Vietnam the
Sino–Vietnamese ruling elite, with the backing of a relatively ethni-
cally homogeneous Muong/Viet peasantry, were determined to defend
Vietnamese independence. In Dali, the ruling elite was non-Chinese
(probably belonging to a tribal people known as the Lolo) and ruled
over a highly ethnically diverse population with less clearly defined
loyalties. In such circumstances, Chinese settlers, especially locally
powerful families, retained their cultural allegiance to what for them
was their own superior civilisation. Another reason was that for three
hundred years before the Mongols invaded, Vietnam had faced a more
uncertain, more competitive, and more strategically sensitive political
and economic environment than had Dali. Trade, both tributary and
non-tributary with China and commercially with other parts of South-
east Asia, was always more important than it was for landlocked Dali.
Moreover, while Vietnam faced a security threat from Champa to the
south as well as from China, Dali encountered no such southern threat
A Short History of China and Southeast Asia