What is outland of World of Warcraft? How did he get here?

There are many parallel worlds in wow's settings. It can be considered that, like many planets in the universe, Azeroth is the earth, and the others are Mars, Mercury and Neptune, so people often call Outland Mars.

Outland used to be a world called Delano, the hometown of orcs. Delaney people came to Delano from other worlds and settled down. At first, the world was as beautiful as Azeroth (all places like Nageland also had seas), but Kilgardan lured orcs to slaughter Delaney people, which led to war, led demons to Delano and polluted the world and the orcs themselves, so Delano became a hellfire peninsula.

After that, the orcs invaded Azeroth, and many things happened. Later, allied troops wore