The Tarim Basin's rivers flow inland and vanish in the desert
Meltwater from the mountains ringing the Tarim Basin never reaches an ocean. Most rivers running north from the Kunlun die in the sand, and the Tarim River itself ends in the salty, now-dry hollow of Lop Nur. When that river shifted course around 330 AD, a whole Silk Road city was abandoned.
The basin covers about 888,000 square kilometres, the largest in northwest China, boxed in by the Tian Shan to the north and the Kunlun on the edge of the Tibetan Plateau to the south. Much of its floor is the Taklamakan Desert, too dry for anyone to live in permanently. It formed when an ancient microcontinent fused with a growing Eurasia between the Carboniferous and Permian periods, and today its margins are still being shoved beneath the surrounding ranges. Sediments in the centre are locally more than 15 kilometres thick.
The Yarkand, Kashgar and Aksu rivers merge into the Tarim, which runs along the north side of the basin. Its water once reached the city of Loulan, until, at some point after 330 AD, the channel swung southeast near Korla and Loulan was left to the sand. Of the rivers draining north from the Kunlun, only the Hotan reliably reaches the Tarim, and then only in good years; ruined settlements hint that these streams were once larger. Because the basin is ringed by peaks and farming there probably needed irrigation, it may have been one of the last parts of Asia people settled.
Traders threaded around the desert rather than across it. Silk Road routes followed chains of oases along the northern edge through Aksu, Kucha and Turpan, and along the south through Yarkand and Khotan, famous as China's main source of jade. A middle route ran through Loulan and Lop Nur until the region became uninhabitable in the 4th century, and was deserted by the 6th. Caravans met in Kashgar before tackling the mountain passes west.
Modern engineering has closed the loop. Railways now encircle the whole desert, and the Tarim Desert Highway cuts straight across its centre. Beneath lie large oil and gas reserves, some in wells deeper than 7,500 metres, and in 2015 Chinese researchers reported a vast carbon-rich underground sea under the basin.
Source: Tarim Basin
