Definitely recommended, the volume covers 1929-1941, I am now on p.234. Here is one good “that was then, this is now” bit:
Stalin had fixed a covetous eye on Chinese Turkestan, or Xinjiang (“New Territory”). From January through April 1934, he fought a small war there. Renewal of a mass Muslim rebellion had spurred Comintern operatives to contemplate pushing for a socialist revolution, but Soviet military intelligence had pointed out that, even though the rebels commanded the loyalty of almost the entire Muslim population (90 percent), a successful Muslim independence struggle in Chinese Turkestan could inspire the Kazakhs and Kyrgyz in Soviet Turkestan or even the Mongols. Stalin had decided to send about 7,000 OGPU and Red Army soldiers, as well as airplanes, artillery, mustard gas, and Soviet Uzbek Communists, to defend the Chinese warlord. Remarkably, he allowed Soviet forces to combine with former White Army soldiers abroad, who were promised amnesty and Soviet citizenship. A possible Muslim rebel victory turned into a defeat. Unlike the Japanese in Manchuria, Stalin did not set up an independent state, but he solidified his informal hold on Xinjiang, setting up military bases, sending advisers, and gaining coal, oil, tungsten, and tin concessions. Some 85 percent of Xinjiang’s trade was with the USSR….Chiang Kai-Shek became dependent on Soviet goodwill to communicate with Xinjiang’s capital, Urumqi.
Here is excellent New Yorker coverage of the book from Keith Gessen. You can buy here on Amazon.