Asgard is a realm inhabited by powerful creatures claiming to be Gods. It lays on a branch of Yggdrasill near Svartalfheim. They are ruled by Odin and include Thor, Sif, Balder, Fandral, Hogun, Volstagg, Amora, Loki, Executioner, and Hela.
Loki has tried to take over Asgard many times. Once he brought Bruce Banner and separated the Hulk from him. However, Hulk grew too powerful and nearly killed Thor, defeated nearly all the Asgardians, and nearly brought Ragnarok when he almost killed Odin in his Odinsleep.
Another time Loki tried to use Frost Giant to defeat Asgard but was stopped by Thor. This time Odin sent Loki to the Isle of Silence but Amora rescued him.