First Blight

The First Blight began in 800 TE, approximately 1300 years before the events of Dragon Age: Origins, and lasted nearly two centuries. It was the longest Blight in history.

Background
According to the Chantry, in 800 TE, the magister lords of the Tevinter Imperium entered the Golden City in an arrogant effort to usurp the Maker's throne. For their sinful pride, they were cast out of the Golden City and twisted and cursed by their own corruption, devolving into monsters: the first darkspawn. Shortly after, the darkspawn fled underground.

They swarmed through the Deep Roads, sparking a never-ending war against the dwarves. Every noble dwarven house wished to have their own thaig defended, leading to political chaos and a disorganized defense. Aeducan, of the Warrior Caste, united the armies of the dwarves and led them to defend the city of Orzammar; by this time most thaigs had fallen, and Aeducan chose to hold the line at Orzammar rather than attempt to save the remaining ones. For leading the defense, he was made a Paragon.

By chance or design, the darkspawn located the Old God Dumat in his underground prison and corrupted him, transforming him into the first Archdemon. With Dumat leading them, the darkspawn turned their attention from the dwarves to the surface, and began amassing their numbers for a massive conquest: the first Blight.

The Fall of an Empire
The Tevinter Imperium, a mighty empire that stretched across most of Thedas, became the main target of the Blight. Taken completely by surprise, the armies of the Imperium, more accustomed to bringing down slave revolts or conquering helpless lands, were overrun by the seemingly endless hordes. However, the greatest blow against the Imperium was dealt to its morale. The people of the Imperium couldn't understand why the greatest of their gods, Dumat, had turned on them, and their faith in the magisters faded. Gifts and prayers to the other Old Gods went unanswered. The Imperium fractured as soldiers, ravaged and hopeless, fled from their duties and remote provinces declared independence.

Grey Warden Founding and the Battle of Nordbotten
A group of Anderfel knights, recognizing the threat the Blight posed to all of Thedas, decided to renounce their service to their king and take on a new, more important duty: to defeat the Blight. They formed the Order of the Grey Wardens in 890 TE, at Weisshaupt Fortress in the Anderfels. The process of the Joining ritual was discovered by the knights, who somehow managed to consume both lyrium and potent darkspawn blood together to grant them the ability to sense the enemy.

The Grey Wardens' first official battle was at Nordbotten. Accounts tell of the Wardens swooping into battle upon the now-extinct griffons and decimating the ranks of the darkspawn. The Battle of Nordbotten was the turning point of the First Blight as the inhabitants of Thedas finally started to win decisive conflicts and repel the darkspawn incursion.

Introduction of Golems
Even during the Blight, darkspawn attacks from their lairs in the Deep Roads did not abate. In 940 TE, the dwarf Caridin was made into a Paragon following his design (or discovery) of The Anvil of the Void. The Anvil allowed Caridin to forge a construct of steel or stone with great strength and survivability. They were one of the dwarves' most effective weapons against the darkspawn, but to bring each golem to life required the soul of a living dwarf. Initially, volunteers gave their lives willingly, but controversy arose when there were no more volunteers to be found.

Battle of Silent Fields
Dumat was slain by the Grey Wardens in 992 TE upon the Silent Fields. None of the original Anderfels soldiers survived the battle.

The Grey Wardens
The followers of the original Anderfel knights eventually inherited their customs and duty, officially founding the order of the Grey Wardens to be recognised by all of Thedas.

Rise of Andraste
With the Tevinter Imperium severely weakened by the Blight, the barbarian Andraste called for an Exalted March against the Imperium 28 years later.