Communist falsification of history in Russia and China destroyed a number of important historical documents and made deciphering their past more uncertain.
The communists did not merely write histories praising the government. Nor did they just kill political opponents. The Communists literally erased opponents from historical record. Photographs were doctored to remove individuals. Histories and documents were rewritten to exclude once important men and ideas.
The NKVD chief oversaw many of the initial purges in the Great Terror from 1936 to 1940. As the years went by, more and more NKVD men were purged to keep the organization loyal to Stalin. Yezhov was murdered and erased from existance in 1940. He was replaced by Lavrenty Beria, who would later be executed in 1953. The position of Secret Police Chief lacked job security.
More famously, the Soviets tried to erase Trotsky from existence. Stalin sent assassins to Mexico to murder the exiled Trotsky and silence his criticism of Stalin’s totalitarian regime. Then the propaganda artists went to work, erasing Trotsky from every photo and every record.
How many lesser known individuals were erased from memory? How much history was actually lost? Just another one of the many gifts of communism.