Their travels start in central Asia, in Tajikistan, which is just north of Afghanistan, and enter China in the provinces now known as Xinjiang and Gansu. Their style of writing emphasizes the people, their industry, and their cultural history. It includes lots of local information on their economy, including agriculture, industry, natural resources, population, roads and rail infrastructure at the time. This book concentrates mainly on Xinjiang. Only about 1/6th of the book is on Gansu province, and its capital Lanzhou, the Yellow River and Liuchia hydroelectric dam, and the western stretches of the Great Wall. There is a discussion of a new iron mill, new key bridges, and optical industry which are sensitive strategic assets at the time.
If you can read another contemporary assessment of the region, then you can get a balanced perspective in what changes and advancement have taken place. Since the Silk Road has been a trade route for millennia, the author weaves in ancient history and bring the reader up to speed with British holdings in India and Pakistan, and Sino-Soviet boarder issues at the time.
There is a 10-page introduction into silk culture. They also talk about the subjugation by the PLA Han Chinese on the native Uighur population at the different oasis / cities.
The book does appear to be a mouthpiece of the Chinese propaganda machine as there are many facts and numbers that one needs to qualify the source of such info. Still it gives a frame of reference that you can compare to the author's own experiences and those of other writers.
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Paul Theroux wrote a 28 page chapter in his popular book "Riding the Iron Rooster", Ivy, 88, 0-8041-0454-9, when he visited the area from Lanzhou, Ganzu to Urumchi, Xinjiang by train in 1986, a decade later. He has his best dish of all China in Urumchi, a deep-fried, steamed chili, smoked duck, p189 pbk.
For information on the Silk Road extended into Central Asia, I refer you to Calum MacLeod, etal, Uzbekistan: the golden road to Samarkand, by Odyssey, 1999, 962-217-582-1