Sum up :
From the early 20ies to the late 60ies, USSR’s Politburo, sent to prison massive number of people [around 20 million]. Many of them died, on the way to their camps or in detention because of harassing tasks, very poor life conditions and undeniable lack of food.

Escaping prison south, even if long and geologically extreme was the only way that was acceptable.
They still had to go through the iron curtain

. Walking, riding, hiding through steppes, forests, swamps deserts and mountains ranges were to be defeated over 6000km of a lifetime escape.