(reigned 1177–1215?), and the disunity of the Mon, than by such
tenuous linkages. A power vacuum existed in central mainland South-
east Asia, and the Tai filled it.
Several small Tai principalities (meuang) had come into existence
as early as the first half of the thirteenth century in what is now south-
ern China (Chiang Hung), in northern Thailand (Chiang Saen) and
as far south as Sukhothai, in northeastern Burma on the Shan plateau,
and as far west as Assam. It seems likely that these principalities
accepted Mongol hegemony in return for a free hand in their struggle
against the Mon and Khmer. By the second half of the century, charis-
matic rulers were able to weld together larger kingdoms. King
Ramkhamhaeng (reigned 1279?–1298?) expanded Sukhothai to become
a powerful Tai kingdom comprising most of central Thailand and
stretching east as far as Viang Chan, south down the Kra Isthmus to
Ligor, and west to Pegu. To the north King Mangrai conquered the
former Mon kingdom of Haripunjaya (1281) to form the kingdom of
Lan Na. In 1292 he established his new capital at Chiang Mai.
The only threat to expanding Tai power came in 1287 when the
Mongols invaded Pagan for the second time. The three most powerful
northern Tai princes came together the same year to conclude a pact
to oppose any Mongol invasion of their territories. When Chiang
Hung fell to Yuan forces in 1292, Mangrai came to the aid of its ruler
and retook the city. Four years later the city again twice changed
hands. A major Mongol campaign in 1301 turned out to be a complete
disaster, and only emboldened the Tai to raid further north into
Chinese territory. At length diplomacy won the day. King
Ramkhamhaeng of Sukhothai had sent his first tribute mission to
Beijing in 1292, in response to the arrival of a Chinese mission ten
years earlier inviting Sukhothai to acknowledge Chinese suzerainty.
The delay may have reflected Siamese resistance to this, and the
mission, when it was despatched, may have been a shrewd insurance
measure, given events in Burma and Java, against possible Mongol
intervention (which, as we know, was requested by Lopburi). This first
Mongol expansionism