Shattrath City, a city buried deep in the mountains and valleys, was where the draenei lived after they were exiled from Draenor.
When Sargeras deceived and recruited the eredar of Argus, among the three leaders of the eredar, Archimonde and Kil'jaeden fell to temptation, while the prophet Velen saw through the lies of the Dark Titan through a prophecy and chose to reject Sargeras.
But this rejection also caused Velen to have no place on Argus. He could only leave the eredar race with some of his eredar followers and escape from Argus on a starship. Along the way, the Burning Legion hunted down Velen and his followers, and in the end, because the starship was damaged, they fell onto Draenor.