I’ll add a bit to what Russ says her e about the detestable letter-to-the-editor by a history professor (living in North Carolina) on the alleged humanity of China’s Cultural Revolution.
First on the death toll of that tragic episode; I quote here from page 513 of The Black Book of Communism  (1999):
By comparison with the terrifying but almost unknown horrors of the agrarian revolution and the Great Leap Forward, the effect of the "Great Proletarian Cultural Revoluion" seems almost modest. Estimates vary greatly for the number of dead: most authors cite figures between 400,000 and 1 million, although [Jean-Luc] Domenash calculates between 1 million and 3 million.
And here is the great historian Richard Pipes (from page 131 of his 2001 book Communism ) on China’s Cultural Revolution:
For several years China, one of the oldest civilizations in the world, was ravaged by barbarian hordes who had been taught to treat everything beyond their understanding as fit for destruction. At its height, all schools were closed and no books were available except for textbooks and Mao’s own works. Performances of western music were forbidden. The Red Guards assaulted intellectuals and forced them to humiliate themselves publicly; they tortured and killed many of them….
Although anyone in China who dared to criticize either the Great Leap Forward or the Cultural Revolution risked immediate imprisonment, not a few radical intellectuals in the West sympathized with Mao’s barbarities and sought wisdom in his inspired writings.
Some things — not least some western intellectuals’ gullibility to their own imaginations — remain, regrettably, the same.