Tinfoil Hats on. Let's speculate. Let's make some things up.
To be honest, I'm not one hundred percent sure that what I'm about to write is a TFH entry. It's more just speculative about the nature of the Iron Horde and the Draenor it seeks to rule, and the consequences of its rise. Since I can't actually know any of that yet, it's certainly speculative, but I have no grand theory in mind to explicate, just a bunch of speculations to lay out.
What we know so far is actually only a tantalizing veneer over all we don't know. From the time of the initial incursion that creates this new Draenor to the time that we become aware of it, a certain amount of time has to pass - it takes time to outfit an entirely new kind of army, much less create a new Dark Portal and usurp the connection to our Azeroth's Dark Portal and invade it, which we've been told will be happening. This leads to a whole host of questions - what happens during that period of time? How does Garrosh convince the orcs of Draenor that they should listen to him, a completely unknown quantity? He won't be from any tribe they know of - while he's a member of the Warsong by blood, none of them will recognize him. How does it happen?
I'm fascinated by the idea of this moment. Does he just flat out tell them who he is and where he comes from? While Garrosh is a very cunning tactician capable of deceit, he's also fairly straightforward, so I can imagine him infiltrating the tribal society of orcs on Draenor or simply strolling up to a Kosh'harg and declaring who he is. Either approach has risks, of course - while violence is forbidden at a Kosh'harg, he could easily be laughed right out of the place, and infiltrating an orc tribe would be very difficult for an outsider.
This is fascinating because it implies that Gul'dan this time around betrayed Ner'zhul before the elder shaman had so thoroughly offended the elements and ancestor spirits that he could no longer work shamanic magic - and this seems confirmed by the Ner'zhul entry.
Indebted to a demonic lord and pitted against the mentor he betrayed, Gul'dan is one of a handful of fel orcs on Draenor, his visage and shamanic power twisted balefully by demonic communion. The outcasts he leads, the Stormreaver clan, now fight to wrest their "rightful" place in the Iron Horde from Gul'dan's former master Ner'zhul . . . and to tempt a great army of orcs into infernal corruption.
- Chieftains, Gul'dan, from Warlords of Draenor official site
In the established timeline, Ner'zhul was one of the most powerful and revered shamans his people had, a master of speaking to the ancestor spirits. It seems this continues - but it also seems that this time, Kil'jaeden may have simply chosen Gul'dan over Ner'zhul from the start, which implies that Garrosh's actions changed things further back than we previously understood. Ner'zhul's initial uniting of the orcs at Kil'jaeden's behest seems also to have not happened to this Draenor, and the consequences of that change are staggering, and explain much.
Though Ner'zhul is contemplative and forward-thinking, his vision of a united orcish culture has been eclipsed by the manipulations of his apprentice, Gul'dan, and the bloody reality of the rising Iron Horde. His clan, the Shadowmoon, has always looked reverently to the stars to guide their fellows. Today, the mysticism of these death-sages nudges Draenor closer to obliteration.
- Chieftains, Ner'zhul, from Warlords of Draenor official site
If you're familiar with the history of the rise of the Horde, you know that one of the greatest battles (and most decisive) was the sacking of Telmor. The destruction of Telmor was the beginning of the end for the draenei, and it came about at the tail end of the campaign Ner'zhul started against the draenei at Kil'jaeden's behest. This campaign led Ner'zhul to lose the favor of the ancestors and the elementals, and in turn when he turned his back on Kil'jaeden it led Gul'dan to betray him and swear allegiance to Kil'jaeden. So if we prevent all of this - if Garrosh's Iron Horde begins its rise in a way that prevents Ner'zhul from making his mistaken pact with Kil'jaeden (disguised first as Ner'zhul's dead mate Rulkan) - then we don't see Telmor destroyed by Durotan, and this explains how the Draenei in this Draenor can still be fighting.
But that's the interesting thing about the draenei. They didn't come from Draenor. We're often told of their origin - how they originated on a world called Argus, how they were driven into exile when Sargeras the Dark Titan came and offered their people, the eredar, the power to help him conquer the universe, and those that refused became draenei, exiled ones in the eredar language. We know this. We know that after repeatedly staying one step ahead of their fallen brethren, the draenei crashed to the world that would become known as Draenor (exile's refuge in their language) and became an aloof part of this new world, while the naaru dimensional ship they'd used became Oshu'gun, the sacred diamond mountain of the orc people. The orc ancestor spirits came to Oshu'gun drawn by the recuperating naaru K'ure.
But what, exactly, is a dimension ship?
A dimension ship travels between alternate realities. Like, as an example, this alternate Draenor and our Azeroth. This leads us to one, inescapable conclusion - Argus, and the draenei (and the eredar for that matter) and even the naaru are not necessarily from the same universe, the same reality, as Azeroth. They traveled to Draenor on a dimension ship - and it may be that fact, that constant travel through alternate realities that made them so hard for the Burning Legion to find in the first place. How many universes have the draenei visited... and how many divergent realities have they created by suddenly existing in a space and time where they did not exist before?
The draenei 'nether-ship' you've been hearing about is far more than it seems. It's part of a larger dimension-traveling fortress called Tempest Keep that essentially teleports through alternate realities.
- Chris Metzen
Put another way - the draenei may not just be from another world. They may be from another reality altogether. In Azeroth's reality, the draenei may not even exist - the world Argus may be the same world as Azeroth, just with a different name, in a reality where the Old Gods never visited it and the eredar evolved naturally. Or perhaps not - there's no way to know at present. There may well be an Argus in our Azeroth's universe, with a bunch of eredar on it who have never heard of Sargeras, with an Archimonde, Kil'jaeden and Velen on that Argus who are all friends and brothers leading a happily oblivious people to greater and greater heights of magical knowledge, safe in their ignorance of what their counterparts are doing.
Questions with no answers. But what we do know is this - it is likely that this particular circumstance, where draenei travel back to an alternate reality created by someone else - has never occurred in their history. And it leads us to wonder about the very nature of our Azeroth, which Velen has stated will be the place where the final battle between Light and Shadow will be fought. Once the Exodar (itself a dimensional ship, part of an even larger dimensional ship) arrived in our reality, did it change the course of our history? Is that the true secret of Velen's prophesies - his first major vision we're privy to is the one he gained when Sargeras visited Argus. Does Velen sort through potential futures, seeing alternate realities and how they would unfold?
So we have the arrival of the draenei on Draenor from not just another world, but from another reality, and their presence altered Draenor forever - not only did they name a world that had no name before them, or at least not one the orcs cared about (the ogres may have named it when they ruled the world in its distant past) but their very presence may have changed its history. They were an outside element, from another space and time entirely, travelers on a crashed dimensional ship that altered even the very religion of the native orcs. Without their arrival, the world that produced Garrosh Hellscream would have been fundamentally different - and in turn, he then wouldn't have traveled to Azeroth, become Warchief, and eventually traveled across space and time himself to alter history and create another Draenor. It folds back in on itself. And what's so amazing about it is, it may have happened before - because we know the draenei arrived on Draenor via dimension ship, it implies that there's a whole host of Draenors out there that aren't named Draenor.
There could be an infinite array of worlds populated by orcs and ogres and gronn which have no Oshu'gun, no draenei, no Legion and no Horde. An infinite array of Azeroths which have never seen an orc, where Medivh still plots with Sargeras in his soul, where the Kaldorei never saw humans and orcs, where Pandaria still slumbers behind its mists. Our Azeroth is special because improbability piles up on top of improbability here - the draenei, having traveled again and again between alternate realities, have led all the cascading changes of their track right here to our shores. They traveled to the Draenor we know, and all the changes that followed that arrival made the Horde possible - the centralized worship at Oshu'gun made orc unity more than theoretical, led Kil'jaeden and his hounds to the orcs, gave Ner'zhul and Gul'dan an enemy to point the new Horde towards destroying. Change after change, because K'ure crashed through the dimensional barriers with his exiles in tow, and deposited them like a boulder in a stream bed to split the waters into new pathways. And all of those changes, all of those alterations, piled up like rocks in a landslide to lead us to the Azeroth where the final battle can be held.
And now it draws near to another recursion, another Draenor, ripples bouncing off the shore to return to where the rock originally crashed through the water. Echoes of what is past, or passing, or to come.
While you don't need to have played the previous Warcraft games to enjoy World of Warcraft, a little history goes a long way toward making the game a lot more fun. Dig into even more of the lore and history behind the World of Warcraft in WoW Insider's Guide to Warcraft Lore.