Who Built the Turpan Oasis Karezes - and When?

When Were the Marvelously Engineered Qanats of Turpan Oasis Built?

Ruins of the Jiaohe City in the Turpan Oasis
Ruins of the Jiaohe City in the Turpan Oasis. moniqca

The Turpan Karez system of Xinjiang province, China, is one of the world's marvels of water control engineering. At some point in the past, over one thousand underground wells and tunnels called qanats or karezes were excavated within the Turpan oasis, to increase the amount of water which naturally flowed into the important oasis on the Silk Road. But one of the great mysteries has to do with when the system was constructed.

An Open Question

Estimates from archaeologists and historians about when the qanats were built in Turpan vary widely. Eric Trombert's research (2008) asserts that the majority of the qanats were built no earlier than the late 19th century AD; other scholars argue for at least a Tang dynasty date (618-907 AD) and some even suggest they were built during the Han dynasty takeover of the Turfan Basin, in 90 BC. All of these argue that it was the Chinese government who instituted the construction of the massive qanat system.

But, qanat technology is a Persian invention, and the Subeixi culture people who were living in the Turfan Basin when the Han dynasty invaded were descended from the Persians. The Subeixi were Steppe Society nomads with broad Eurasian contacts: they grew and traded a wide range of animal and plants from both east and west.

If the qanats do date to the Han dynasty, qanat technology could well have been part of the Subiexi traditional knowledge, even if the network was established by Han dynasty rulers.

If instead the qanats date to the Tang dynasty, the Uighurs were resident in the Turfan Basin during that period. The Uighurs are a Turkic Central Asian people who still reside in Xinjiang.

The Uighurs are Muslim, and the Islamic civilization is credited with the spread of qanat technology into Spain and Northern Africa. Further, according to the Muslim mathematician Abu Bakr Al-Karaji, the technology was held by a heriditary guild of diggers. If the qanats date to the Tang dynasty, qanat technology could well have been part of Uighur traditional knowledge: certainly the word "karez" is a Uighur term; the Chinese word for qanat is "kan'er jing" which Trombert argues is a semi-phonetic version of karez.

Could the Qanat System Date to the 19th Century? 

However, Trombert's research suggests that neither the Han nor Tang rulers of Turfan were aware of qanat technology, and that it was only during the Qing dynasty (1644-1912) that karezes were excavated on a mass level. Trombert suggests that the General Governor of Urumqi first discovered a working qanat in Turpan near the Subiexi city of Jiaohe in 1807. In 1845, the Qing dynasty scholar Lin Zexu, says Trombert, discovered karezes in use by Turfan's peasants especially for growing cotton, a crop that consumes an immense amount of water. It was on Lin Zexu's recommendations that karez technology was instituted in Turfan on a large scale in the early 19th century.

So, the question still is: who brought karezes to the Turpan basin, and when did that happen?

How to Date a Karez...

From an archaeological standpoint, the real difficulty in figuring out who built the qanat system--or at least the first karezes--is trying to peg a date on when a specific qanat was constructed. Methods of qanat construction are remarkably conservative: qanats built by hand in 6th century BC Persia are quite similar to those built by hand in the 19th century AD. Putting a date on a specific qanat is typically achieved by indirect association with adjacent settlements, or the discovery of diagnostic artifacts incorporated in the sediments that are upcast from ventilation shaft excavation.

That only works if there are artifacts in the spoil piles.

Bailiff et al. (2015) have tried a technique using Optically Stimulated Luminescence (OSL) on the soils in spoil piles deposited around the ventilation shafts, which were presumably built up during cleaning periods. OSL determines when the soil was disturbed for its original location. Their results returned dates that were broadly consistent with the artifacts found in the spoil piles. Their research is a pilot study conducted on Medieval Spanish qanats, and it remains to be seen if the method can be used consistently elsewhere.

Who First Built the Turpan Qanats?

It seems clear that the Turpan Oasis was historically lush before the qanats were built, and the qanats were instituted at some point by people who were responding either to population increase, climate change, or the demands of increased agricultural intensification. The massive levels of construction may well have occurred in the 19th century at the behest of the Chinese government, but the technique was one that the indigenous people of the Turfan basin already knew and were using.

How long the people of Turpan Oasis used karezes before the massive system was built is still an open question.

Sources

This article is a part of the About.com guide to the Silk Road, the guide to the Ancient Societies of the Central Asian Steppes and the Dictionary of Archaeology.

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