The permafrost of places like Siberia is not so permanently frozen any more.
As it slowly melts, wonderful things are emerging, some frozen for tens of thousands of years.
Baby mammoths are sometimes found in an extraordinary state of preservation.
In other places which are not as frozen as they were, other amazing discoveries have been made.
In 1991 two hikers in the Alps found a body.
They were shocked, and reported the find.
It was even more extraordinary when the investigation found that the body was thousands of years old.
The clothing, weapons and other items found with the body give a glimpse into life when metal was first being used.