Open air labor camps/jails frequently far removed from civilization, some where very bad, some where tolerable. Used to labor, particularly mining in far removed places and building stuff with not so good worker safety conditions. Despite western non-sense, mainly populated by criminals, but conditions still were not humane somewhat frequently, especially in building projects (as far as I know, mining/channel building were the worst offenders, while forestry was mainly tolerable). Sort of continuation of katorga from tzarist russia, which explains their form, but doesn’t excuse it. Also sentences in ussr (in that period) were either less than 3 years and carried out without gulag involvement, or 5 to 10 (for crimes more than 10 years “worthy”, death penalty was the punishment). It’s all from memory, so maybe some comrades can correct me.