New history textbooks for high schools in Russia have been found to harshly criticize North Korea’s political system.

Three history professors at Lomonosov Moscow State University jointly wrote the books, which will be used by high school seniors starting in September.

The books noted that the North’s government publicly denounced revisionists during the 1960s and 1970s and either sent them to prison, forced them to do hard labor or killed them.

The book says that due to the absence of political freedom and the state’s complete control over the economic system and the media, the North’s 23 million citizens live in poverty completely isolated from the outside world.

Meanwhile, the textbooks described South Korea as having achieved remarkable economic growth and industrial development.