If the Warden is a dwarf...
The surfacers claim that the first darkspawn fell from heaven. They spin tales of magic and sin. But the Children of the Stone know better. The darkspawn rose up out of the earth. For it was in the Deep Roads they first appeared. Creatures in our own likeness, armed and armored, but with no more intelligence than tezpadam, bestial and savage.
At first they were few, easily hunted and slain by our warriors. But in the recesses of the Deep Roads, they grew in numbers and in courage. Our distant thaigs came under attack, and now it was the army, not a few warriors, being sent to deal with the creatures. Victories still came easily, though, and we thought the threat would soon be over.
We were wrong.
If the Warden is not a dwarf or in Dragon Age II...
Those who had sought to claim
Heaven by violence destroyed it. What was
Golden and pure turned black.
Those who had once been mage-lords,
The brightest of their age,
Were no longer men, but monsters.
No one knows where the darkspawn come from. A dark mockery of men, in the darkest places they thrive, growing in numbers as a plague of locusts will. In raids, they will often take captives, dragging their victims alive into the Deep Roads, but most evidence suggests that these are eaten. Like spiders, it seems darkspawn prefer their food still breathing. Perhaps they are simply spawned by the darkness. Certainly, we know that evil has no trouble perpetuating itself.
The last Blight was in the Age of Towers, striking once again at the heart of Tevinter, spreading south into Orlais and east into the Free Marches. The plagues spread as far as Ferelden, but the withering and twisting of the land stopped well beyond our borders. Here, darkspawn have never been more than the stuff of legends. In the northern lands, however, particularly Tevinter and the Anderfels, they say darkspawn haunt the hinterlands, preying on outlying farmers and isolated villages, a constant threat.
--From Ferelden: Folklore and History, by Sister Petrine, Chantry scholar.