Theterritorial losses of Thailand is a concept in Thai historiography, referring to conflicts during theRattanakosin period ofThailand (or Siam as it was historically known) where the country was forced to cede territory, especially to the Western powers of France and Great Britain during the reign of KingChulalongkorn (Rama V, 1868–1910).

The concept was popularized in the 1930s as part of theThai nationalism promoted by the government ofPlaek Phibunsongkhram. The idea was propagated through sets of maps, titled theHistorical Atlas of Thailand andMap of the History of Thailand's Boundary, that claimed to depict the historical extent of the boundaries of Thailand's predecessor states and the territories it subsequently lost. The maps have been widely disseminated, especially through their inclusion inThongbai Taengnoi's student atlas, a standard textbook used in Thai schools since 1963.

While later historians have disputed the maps' historical accuracy, the concept remains a mainstay in Thai nationalist discourse, and has re-emerged especially during episodes of theCambodian–Thai border dispute.

The concept of Thailand's territorial losses was first popularized in the 1930s as part of the anti-WesternThai nationalist ideology promoted by the government ofPlaek Phibunsongkhram (Phibun). The loss of territories was leveraged as a theme in "national humiliation discourse"—as termed by historian Shane Strate—which was employed to bolster support for the government and itsirredentist ideology ofPan-Thaiism.^[1][2]

The idea was publicized through a set of maps titled the Historical Atlas of Thailand and another map called the Map of the History of Thailand's Boundary. The Historical Atlas is a set of six maps, the first depicting the southward movement ofTai/Thai people from theAltai Mountains, (as was a popular theory at the time) and the others depicting the territories of the Thai kingdoms ofNanzhao (considered so under said theory),Sukhothai during the reign of KingRam Khamhaeng,Ayutthaya duringNaresuan's,Thonburi duringTaksin's andRattanakosin duringRama I's.^[3]

The History of Thailand's Boundary is a single map, labelling territories lost by Thailand over several occasions, resulting in the country's present-day shape. Several versions of the map exist, with differing accounting of the losses, but all include the cession of territory that is now Laos and Cambodia to the French in 1893, 1904 and 1907, and of the four Malay states to the British in 1909.^[3]

The Historical Atlas of Thailand series (six plates, left) and Map of the History of Thailand's Boundary (right), in the most widely recognized version depicted in Thongbai Taengnoi's atlas

The Historical Atlas set of maps was first published by theRoyal Thai Survey Department around 1935–1936.^[4] The History of Thailand's Boundary map (also referred to as Evolution of the Boundary of Thailand) was also first produced in 1935, though it was a different version that rose to prominence in 1940, amid the spread of the Pan-Thaiist ideology supported by Phibun's government, with calls for the return of territory ceded to the French in 1904 and 1907. The map was distributed to schools and government offices, prompting protests from British and French diplomats. The government distanced itself from the publication, but its distribution was then taken up by one of Phibun's aides.^[3]

The movement gained widespread public support, and Thailand under the Phibun governmentinvaded French Indochina in 1940 to reclaim the lost territories. Thailand briefly annexed some of the territories thanks to its alliance with Japanduring World War II, but had to renounce the claims after the war. Despite the changed political climate, the maps continued to live on thanks to their adaptation into school material.

In 1957, Phunphon Atsanachinda, a former Royal Survey Department officer and professor at Chiang Mai University, produced a similar set of maps (including the six Historical Atlas maps and the boundary history map) forThai Watana Panich, one of the largest publishers of school textbooks, titled Bandai Prawattisat Thai Tae Boran (บันไดประวัติศาสตร์ไทยแต่โบราณ, 'the steps of Thai history since antiquity'). It was sold as sets of posters, and became widely distributed among schools.^[5]

In 1963, another version of the set was included in a student atlas illustrated by Thongbai Taengnoi, a school headteacher from Prachin Buri. Thongbai's atlas, also published by Thai Watana Panich, became an extremely popular textbook and was widely used by schools all over the country into the 21st century, with its 44th printing in 2014.^[6] Most Thai people have since become acquainted with the maps through its use in Thongbai's atlas.^[3][7]

Several other versions of the maps, especially the History of Thailand's Boundary, have also been produced, some by historians discussing the historical issues,^[3] others by organizations or groups using them for political purposes, especially those surroundingterritorial disputes with Cambodia. Following the attack of the Thai embassy in the2003 Phnom Penh riots, the Survey Department released a new Map of Siam's Territorial Losses, which claimed thirteen losses as opposed to the around eight usually depicted in earlier maps. Afterthe flare-up of the Preah Vihear dispute in 2008, a widely circulated anonymous online video featured another version with up to fourteen losses.^[5]

The maps are not factually accurate. The Historical Atlas systematically overstates the extent of territories under Siam's control, and selectively depicts only time points of greatest territorial extent, ignoring the ebbs and flows in between. The representations are also anachronistic, as the concept of geographical territories was not recognized in those times, and does not reflect themandala tributary system of the region.^[4] The depiction of the Altai Mountains origin theory suggests that the Historical Atlas was strongly influenced byKhun Wichitmatra's bookLak Thai, a popular account which became adopted into mid-20th century conventional historiography. The theory it is based on—that Nanzhao was a Tai state—has been widely discredited by historians since the 1980s, though it continues to be reproduced in Thongbai's atlas.^[7]

Likewise, the boundary history map provides no basis for the claims it makes of areas historically belonging to Siam, and creates an illusion that the country had a distinct geographical shape before the loss of those territories, while in reality those boundaries had never been clearly demarcated.^[3]

Later historians, beginning withThongchai Winichakul in 1994, have viewed the maps as a political tool, used to strengthen the Thai nationalist view of history. According to Thongchai, they are "not for a study of historical geography, but for historical consciousness about the life of the nation".^[3]Charnvit Kasetsiri has mentioned Thongbai's atlas as an example of how outdated concepts are still perpetuated by school textbooks, allowing nationalist sentiments to be stoked up by political groups.^[8]

The concept remains a mainstay in Thai nationalist discourse, and has re-emerged especially along with the Preah Vihear dispute, which itself has become regarded as one of the losses in the recent versions of the map and list that proliferated in the 21st century.^[5]

• Century of humiliation, a similar application in Chinese historiography

• Strate, Shane (2015).The Lost Territories: Thailand's History of National Humiliation. University of Hawai'I Press.

• Historiography of Thailand
• Thai nationalism
• Rattanakosin Kingdom
• Territorial evolution
• 20th-century maps and globes
• Maps of the history of Asia

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