Khorat Plateau

Khorat Plateau
ที่ราบสูงโคราช
Natural region
Landscape of the Khorat Plateau
Landscape of the Khorat Plateau
A map of the Khorat Plateau region
A map of the Khorat Plateau region
CountryThailand
Elevation
200 m (660 ft)

The Khorat Plateau (Thai: ที่ราบสูงโคราช; Northeastern Thai: ที่ฮาบสูงโคราช) is a plateau in the northeastern Thai region of Isan. The plateau forms a natural region, named after the short form of Nakhon Ratchasima, a historical barrier controlling access to and from the area. Prehistoric and Iron Age settlement is well attested there, notably the moated sites of the Mun and Chi valleys. The region has conventionally been placed under Dvaravati and then Khmer suzerainty, though how its sites related to any state remains unclear.

Geography

The average elevation is 200 metres (660 ft) and it covers an area of about 155,000 square kilometres (60,000 sq mi). The saucer-shaped plateau is divided by a range of hills called the Phu Phan Mountains into two basins: the northern Sakhon Nakhon Basin, and the southern Khorat Basin. The plateau tilts from its northwestern corner where it is about 213 metres (699 ft) above sea level to the southeast where the elevation is only about 62 metres (203 ft). Except for a few hills in the northeastern corner, the region is primarily gently undulating land, most of it varying in elevation from 90–180 metres (300–590 ft), tilting from the Phetchabun Mountains in the west down toward the Mekong River.: 1  The plateau is drained by the Mun and Chi Rivers, tributaries to the Mekong that forms the northeastern boundary of the area. It is separated from central Thailand by the Phetchabun Mountains and the Dong Phaya Yen Mountains in the west, the Sankamphaeng Range in the southwest and by the Dângrêk Mountains in the south, all of which historically made access to the plateau difficult.

These mountains together with the Truong Son Range in the northeast intercept much of the rainfall, so the southwest monsoon has much lower intensity than in other regions. The mean annual rainfall in Nakhon Ratchasima is about 1,150 millimetres (45 in), compared with 1,500 millimetres (59 in) in central Thailand. The difference between the dry and wet seasons is much greater, which makes the area less suitable for rice. The portion known as Tung Kula Rong Hai was once exceptionally arid.

Geology

The plateau uplifted from an extensive plain composed of remnants of the Cimmerian microcontinent, and terranes such as the Shan–Thai terrane, either late in the Pleistocene or early in the Holocene Epoch. Much of the surface of the plateau was once classified as laterite, and layers that can easily be cut into brick-shaped blocks are still so called, but the classification of soils as various types of oxisols is more useful for agriculture. Oxisols of the type called rhodic ferralsols, or Yasothon soils, formed under humid tropical conditions in the early Tertiary. When portions of the plain uplifted as a plateau, these relict soils, characterized by a bright red color, wound up on uplands in a great semicircle around the southern rim. These soils overlie associated gravel horizons cleared of sand by field termites, in a prolonged and still on-going process of bioturbation. Xanthic ferralsols of the Khorat and Ubon Series, characterized by a pale yellow to brown color, developed in midlands in processes still under investigation, as are those forming lowland soils resembling European brown soils.

Archaeology

Many sites of prehistoric Thailand are found on the plateau, including bronze objects of the Dong Son culture. The World Heritage Ban Chiang archaeological site, discovered in 1966, yielded evidence of bronze making beginning c. 2000 BCE, but lacking evidence of weaponry so often associated with the Bronze Age in Europe and the rest of the world. The site appears to have once been part of a broader culture, until abandoned c. 200 CE, not to be resettled until the early 19th century. Non Nok Tha in the Phu Wiang District of Khon Kaen yielded evidence of an Iron Age settlement dating from about 1420 to 50 BCE.

Paleoenvironmental evidence from the plateau indicates a decline in moisture from the mid-2nd century BCE, and increasing dryness with low seasonal rainfall between the 1st and 8th centuries CE, which affected dry rice production.: 236  The moats dug around mounded sites in the Mun valley were among the responses to that change. They would have allowed water to be managed for wet rice, and may have made possible a rice surplus with significant social and political consequences.: 236  Large animals were corralled and domesticated in Iron Age communities on the plateau, and meat consumption rose afterwards.: 236  Moated settlements multiplied in the Mun and Chi valleys, and their construction has been read as under way during the later first millennium BCE, on the ubiquity of Iron Age occupation within them and the absence of later occupation at some, though no firm dates had been obtained. The plateau is the most arid part of Southeast Asia, where the dry season runs from November to May. The moated sites were also centres of salt production and iron smelting. No Neolithic settlement has been identified for the lower two-thirds of the plateau. Little evidence has been found here for iron applied to weapons of war, against the central importance of militarism on the Yunnan Plateau, in Lingnan, and in Bac Bo. The reservoirs of Angkor have been read as serving the same purpose as these earlier moats.: 33, 34, 37 

The plateau holds the ruins of Khmer rest houses about 25 kilometres (16 mi) apart, a comfortable day's walk, along the Khmer highways. They served as hospices and libraries as well as places of rest, and typically included a baray (pond). Muang Sema [th] and Muang Fa Daet are notable for their religious structures, including sema stones at Muang Fa Daet.: 312–316  The region has conventionally been described as having been under the suzerainty of Dvaravati and later of the Khmer Empire. Archaeologist Charles Higham stated, "...we remain largely unaware of the relationships between sites and the presence or otherwise of states on the Khorat plateau" during the 7th to 11th centuries.: 312–316 

Miriam Stark treats the plateau and the Tonle Sap plain to the south as a single cultural region, on the ground that the archaeological material of the two shows similarities from no later than about 500 BCE.: 192  What the exchange across the region amounted to is disputed. From their work in the upper Mun valley, McNeill and Welch concluded that long-distance trade must have been limited between about 500 BCE and the turn of the era. The sites there hold few artifacts that can be traced to anywhere outside the basin. Higham and Vincent describe instead a prestige-goods economy, in which elites secured competitive alliances by exchanging goods. Stark reports that interpretations vary and prefers neither.: 196 

History

The centuries of the Post-Angkor Period are poorly recorded. The plateau seems to have been largely depopulated after that period and a long series of droughts during the 13th–15th centuries. The Lao settlements were found only along the banks of the Mekong River and in the wetter northern areas such as Nong Bua Lamphu, Loei, Nong Khai, with most of the population inhabiting the wetter left banks.

This began to change when a period of Lao prosperity and cultural achievement under King Surignavôngsa (สุริยวงศา Suriyawongsa, ສຸຣິຍະວົງສາ /sú lī ɲā ʋóŋ sǎː/) (1637–1694) ended in a dispute over the succession. His grandsons, with Siamese intervention, carved out separate kingdoms in 1707, and from these came Louang Phrabang, Vientiane and, in 1713, Champasak. The arid hinterlands, deforested and depopulated after a series of droughts that likely led to the collapse of the Khmer Empire, were occupied only by small groups of Austroasiatic peoples and scattered outposts of Lao mueang in the far north.[citation needed] In 1718, the first Lao muang in the Chi valley, and anywhere in the interior of the Khorat Plateau, was founded at Suwannaphum District, in present-day Roi Et Province, by an official in the service of King Nokasad of the Kingdom of Champasak.

See also

References

  1. ↑ Keyes, Charles F (March 1967). "Isan: Regionalism in Northeastern Thailand". Cornell Thailand Project; Interim Reports Series, No. 10 (PDF). Ithaca: Department of Asian Studies, Cornell University. Retrieved 16 August 2019.
  2. ↑ Bunopas, Sangad; Vella, Paul (17–24 November 1992). "Geotectonics and Geologic Evolution of Thailand" (PDF). National Conference on "Geologic Resources of Thailand: Potential for Future Development". Bangkok. p. 224. Archived from the original (PDF) on 20 August 2011. ...latest Pleistocene early to the Recent regional uplifting must have occurred.
  3. ↑ Lofjle, E; Kubiniok, Jochen (1996). "Landform Development and Bioturbation on the Khorat Plateau, Northeast Thailand". Natural History Bulletin of the Siam Society. 44: 199–216. Retrieved 2 April 2016.
  4. ↑ K. Kris Hirst. "Ban Chiang, Thailand Bronze Age Village and Cemetery". About.com. Archived from the original on 6 December 2010. Retrieved 28 Dec 2010.
  5. 1 2 3 Pedersen, Lucille T.; Domett, Kate M.; Chang, Nigel J.; Halcrow, Siân E.; Buckley, Hallie R.; Higham, Charles F. W.; O'Reilly, Dougald J. W.; Shewan, Louise (2019). "A Bioarchaeological Study of Trauma at Late Iron Age to Protohistoric Non Ban Jak, Northeast Thailand". Asian Perspectives. 58 (2): 220–249. doi:10.1353/asi.2019.0014. Retrieved 10 October 2026.
  6. ↑ Higham, Charles F. W. (1996). "A Review of Archaeology in Mainland Southeast Asia". Journal of Archaeological Research. 4 (1): 3–49. JSTOR 41053110.
  7. ↑ Werner, Ulrich. "Thailand's Ancient Civilizations, Isaan Heartland". Your Guide to Thai Culture. Archived from the original on 3 March 2016. Retrieved 2 April 2016.
  8. 1 2 Higham, C., 2014, Early Mainland Southeast Asia, Bangkok: River Books Co., Ltd., ISBN 9786167339443
  9. 1 2 Stark, Miriam T. (2001). "Mainland Southeast Asia Late Prehistoric". In Peter N. Peregrine; Melvin Ember (eds.). Encyclopedia of Prehistory, Volume 3: East Asia and Oceania. New York: Kluwer Academic / Plenum Publishers. pp. 160–205. doi:10.1007/978-1-4615-1189-2_22. ISBN 0-306-46257-5.
  10. 1 2 Charles F. Keyes (1976). "In Search of Land: Village Formation in the Central Chi River Valley, Northeastern Thailand". In Brow, James (ed.). Contributions to Asian studies. Vol. 9: Population, Land and Structural Change in Sri Lanka and Thailand. Leiden: Brill. p. 47. ISBN 90-04-04529-5.

15°40′N 103°10′E / 15.667°N 103.167°E / 15.667; 103.167