Stalin, to make his five year plan succeed, needed to put in place some work camps. These camps where similar to that of Hitler's but in Stalin's case he took people from all nationalities and races. As seen in the image, Siberia does not look like a place where working conditions would be adequate. By forcing these people to work long and brutal hours in the Siberian cold he indirectly killed over 40 million people.
Harsh Siberian winters caused many of the laborers to die of the cold.