Midgard is one of the nine worlds connected by Bifröst,the rainbow bridge that runs through Yggdrasil. Midgard was the world where humans populated earth.
Ragnarök
Edit
It is said that all humans on Midgard will be wiped out by Ragnarök except a man named Liftraser and a woman named Lif who found shelter in Yggdrasil. In the myth they would re-populate Midgard.
