Draenor has always interested me. Note that I didn't say Outland, which is a part of the former world Draenor. While Outland itself is very interesting in its own right, one of the things I find fascinating about Draenor is that we do not know what it looked like. While we have a good understanding of one large continent (of which most survived as Outland), we don't know the entirety of that continent, nor do we know whether or not any other pieces of the lost red world survived.
What we do know is that Draenor died when Ner'zhul, the former elder shaman and de facto ruler of the Horde remnants that survived Gul'dan's treachery and Doomhammer's defeat, tried to use stolen magical artifacts to open portals to new worlds, hoping to find one to lead his people to settle on. He did this because the warlock magics taught to Gul'dan by Kil'jaeden had effectively rendered Draenor unlivable.
While Draenor was the homeworld of the orcish people, who evolved there, it was not named by them. Rather, it was the draenei fleeing the Burning Legion who gave the world its name. Draenor means "exile's refuge" in the eredun language. In addition, it was the arrival of the draenei and the naaru that led to the entrenched ancestor worship of the orcish people, as K'ure's tomb in Oshu'gun (the remains of the draenei vessel) attracted the spirits of the deceased to it. In turn, these spirits deliberately created a religion among their own descendents that would venerate K'ure's resting place, weaving orc and draenei together spiritually.
Draenor was a world of its own, and we barely knew it. And it's not the only world we know about in the Warcraft cosmos with strange, unexplained mysteries.