incorporated and integrated large numbers of ethnically Laotian people, themselves formed of various subgroups. Siam brought the remaining Lan Xang city-states of Vientiane (destroyed in 1827) and Champasak under direct control in the 19th century. What remained of Lan Na became a vassal until 1896, when it was formally annexed, incorporating large numbers of Kham muang speakers, together with the various ethnic groups sometimes called 'hill tribes', such as the Karen. In the Malay Peninsula, Siam extended formal rule over large numbers of Malay people. In 1816, Siam divided the Muslim tributary Sultanate of Patani into seven provinces as part of a policy of 'divide and rule'. Via administrative modernisation, in 1901 Siam incorporated all seven provinces into ‘Monthon Patani’, under the new Ministry of Interior. When Kedah was ceded to the English under the Anglo–Siamese Treaty of 1909, in exchange for what became Satun Province, Thailand thereby cemented its official rule over hundreds of thousands of Malay people. Siamese suzerainty over present-day Laos, together with some Cambodian provinces, was permanently ceded to the French during the formation of French Indochina. In the early Chakri dynasty period, Siamese armies had invaded areas of Laos and returned with large numbers of prisoners of war, especially Phuan and Tai Dam peoples, who were subsequently resettled in the central plains. During the nation-building era, Siam's ethnic map became more varied, as the majority of the peoples of the Khorat plateau, once part of Lan Xang empire, were formally integrated into Siam, incorporating more Lao, Khorat, and Phu Thai, but also smaller ethnic groups such as the Yoy and So, together with the Khmu, Kuy, and Nyahkur along the Khmer border. As part of Chinese emigration, Thailand received Chinese immigrants over several hundred years, and especially during the nineteenth and early twentieth centuries, until the 1930s, meaning many Thai urban centres now have ethnically Chinese populations (mainly Teochew speakers). Development of Thai ethnocentrism The 1904 Siamese census deliberately omitted the Lao ethnic identity so as to discourage further French colonial predations, resulting in the Thai officially becoming 85% of the population by ethnicity, rising to 89% in 1912. In the 1900s, membership of the Thai 'race' came to form the basis of citizenship of the modern Thai nation-state. In the 1930s, Thai nationalist Luang Wichitwathakan developed ethnocentric policy which came to equate the Tai linguistic family with a greater pan-Thai race-based ‘nation.’ The first