The karez is a peculiarly Central Asian means of irrigation that can be found in Xinjiang, Afghanistan and Iran. Like many dry, arid countries Xinjiang has great underground reservoirs of water, which can transform otherwise barren stretches of land - if you can get the water up.

his subterranean water is often so far underground that drilling or digging for it, with primitive equipment, is virtually impossible. Long ago, the Uyghurs devised a better way.

They dig a karez, knows as the 'head well', on higher ground, where snowmelt from the mountain collects (in Turfan's case the Bogda Mountains).

A long underground tunnel is then dug to conduct this water down to the village farmland. A whole series of vertical wells, looking from above like giant anthills, are dug every 20m along the path of this tunnel to aid construction and provide access.

The wells are fed entirely by gravity, thus eliminating the need for pumps. Furthermore, having the channels underground greatly reduces water loss from evaporation.

Digging a karez is skilled and dangerous work and the karez-kans are respected and highly paid workers. The cost of making and maintaining a karez was traditionally split between a whole village and the karez was communally owned.

The city to Turfan owes its existence to these vital wells and channels, some of which were constructed over 2000 years ago.

There are over a thousand wells, and the total length of the channels runs to an incredible 5000km, all constructed by hand and without modern machinery or building material.

The Turgan oasis is a small city set in a vast tract of grain field and grape wines.

There are hundreds of varieties of Turfan grapes, the best of them are more than ten varieties, including the seedless grape (green), elongated 'mare's nipple', red grape.

With so many varieties of grapes, Turfan produces good-quality wine, both red or white. Very sweet.

Despite the concrete- block architecture of the city centre, it is a pleasant, relaxing place. Some of the smaller streets have pavements covered with grapewine trellises, which are a godsend in the fierce heat of summer.