Lenin liquidated Russia’s Tsarist aristocracy, the bourgeoisie and the affluent peasants known as kulaks. In the 1930s, Stalin killed off most of the first Bolsheviks. The New Class that subsequently emerged in the Soviet Union consisted mostly of technocrats with undistinguished political backgrounds.

Mao was different, and his legacy today is as well. He, too, liquidated landowners. And he sidelined, humiliated and exiled many of his comrades from before 1949. But he did not have them killed off. After he died in 1976, members of the old guard returned to power. They were ousted again later, by Deng after the crackdown at Tiananmen Square in 1989, for sympathizing with the pro-democracy students or resisting Deng’s capitalistic reforms.

That year Mr. Jiang became general secretary of the C.C.P. He wielded formal power or great influence for nearly two decades, including long after he ceased being party chairman, and planted many loyalists in key positions. His people, mostly commoners, amassed personal wealth as China’s economy skyrocketed — to the dismay and envy of many Red Aristocrats.

The Plebeian faction expanded during the first decade of this century, under the leadership of President Hu Jintao and Premier Wen Jiabao: They tapped their power base in the Communist Youth League, a boot camp for commoners wishing to be credentialed for Party membership.

But then came Mr. Xi, a high-carat Red Aristocrat whose father was a senior leader during the republic’s early years. Like a Hamlet kicking out usurpers — a popular comparison — Mr. Xi promptly went after each of the two Plebeian subgroups.

He first aimed his anticorruption campaign exclusively at Plebeians — mostly, in the beginning, at Mr. Jiang’s people but then later also at stalwarts of the youth league. Then in 2016, he openly humiliated the league, cut its funding and placed it under the C.C.P.’s — meaning, his own — control.