Tyr, or Tiw, or Ziw was the god of war and the sky. He sacrificed one of his hands for the good of the gods. In Asgard, the land of the gods, there was a demonic wolf called Fenrir. He was so huge and fierce that only Tyr would dare to approach him. The gods decided to tie the wolf up, using an unbreakable chain forged by dwarfs.