The draenei are a fascinating people to me. Their ability to forgive is terrifying, in a way. This is a people that have seen the majority of their own kind become the stuff of nightmares - a people who have been hunted throughout time and space for over twenty five thousand years by these same fallen former kind, now transformed into demons by their willing adherence to the unthinkable, and it has changed the way they view everything. The draenei are willing to give people who have slaughtered them the benefit of the doubt, and manage to keep their hearts clear (for the most part) of feelings of vengeance and reprisal. The draenei leader Velen went so far as to help the blood elves who had kidnapped and drained the life out of his friend, the naaru M'uru, even through blood elves had stolen Tempest Keep and caused the draenei to crashland on Azeroth in the first place.
We know a reasonable amount about the draenei - we know they come from Argus, that they are refugees, those that chose to heed Velen's warnings and abandon their world before Sargeras could ensnare them in his web of lies and corruption. We know that they've fled the advance of the Legion for that aforementioned two hundred and fifty centuries. What we don't know is how it all went down. What worlds did they arrive on and settle only to have to flee again? Keep in mind that Draenor, the world they named, was only their home for roughly two hundred years out of that vast period of time.
To put it into perspective, Tyrande, Malfurion and the other until-recently immortal night elves, the ones who have lived from the time of the Sundering, are less than half the age of some draenei. Jessera of Mac'Aree, for instance, was fifteen thousand years old at least and had been wandering the cosmos for that long when the Sundering occurred. Not only are the draenei seemingly functionally immortal (they can die, but they do not seem to succumb to old age, or if they do, they have a means to lengthen their lifespans) but they've spent most of that deep time traveling from world to world... and we know almost nothing about that period of their history.