Tai tribes migrated into Southeast Asia between the 7th and 13th centuries AD, especially from what later is
Sipsongbanna,
Yunnan Province and
Guangxi. The possible reasons that actuated Tai migration include
migratory pressures stemmed from Han Chinese expansionism,
Mongol invasions and incursions into Southeast Asia, the area's temperate climate and suitable land for wet rice cultivation, in addition to the fall of states that the Tais inhabited. According to linguistic and other historical evidence, Tai-speaking tribes migrated southwestward to what later are Laos and Thailand from
Guangxi sometime between the 8th–10th centuries. The Tai assimilated or driven out indigenous
Austroasiatic Mon–Khmer peoples, and settled on the fringes of the
Indianized kingdoms of the
Mon and
Khmer Empire. The blending of peoples and the influx of Indian philosophy, religion, language, culture and customs via and alongside some
Austroasiatic element enriched the Tai peoples, while the Tais remained in contact with the other Tai
mueang. The Tai states took advantage of the waning
Khmer Empire and emerged independent. From this point, the Tai states of the
Chao Phraya River valley may be referred to as Siam. While Isan is a multi-ethnic region containing a mixture of Lao, Vietnamese, Cham, Mon, Khmer, and other Tai groups, it is majority Lao, and the Central Thais' perceived threat of Lao cultural and political dominance in the Isan region resulted in
Thaification policies being enacted to finally integrate the multi-ethnic Isan people into Thailand. Since Lao dominance was seen as the greatest threat in the region, 'Lao' was removed as a category in the census, and policies were enacted. References to Lao people or its past were removed and the language was banned from schools and books, erasing Lao influence and impact to the country. The region has become more urban, and cities have sprung up. Due to the larger population and Isan's function as a voting bloc in elections, more attention to improving the region's infrastructure, business and education has come from the national government. ==Geographical distribution==