... about Caucasian Prometey.

At the top of one of the Caucasian mountains, where the eternal snows lay Nart Nasren was rooted with iron chain to a rock. Many centuries he spent there. He was punished by the God Tha for his faithlessness, that he wanted to throw down Tha himself.

That's why the God Tha rooted him to the rock. Many people tried to make him free, but in vain. They died. But narts are said could liberate their Caucasian Prometey. Nobody knows. The mountains keep silent, but the legend lives.