Sanctuary was created as a plane of existence to for the [[Nephalem]], a race of omni-powerful beings birthed from renegade [[angel]] and [[demon]]s who were tired of the war. The powerful [[demon]]ess [[Lilith]] and the [[Archangel]] [[Inarius]] were the prime powers behind this, and their offspring were called [[Nephalem]].

When the [[High Heavens]] and the [[Angiris Council]] found out about Sanctuary, they felt it was an abomination and designated [[Tyrael]] to take the [[Heavenly Host]] and destroy the entire world. The selfless sacrifice of [[Uldyssian]] to save Sanctuary changed Tyrael's mind, and in the end he his was the weighing vote to leave Sanctuary unharmed.

He was the last to vote and while both [[Auriel]] & [[Itherael]] voted for its existence and only [[Imperius]] had voted for destruction, had Tyrael voted in favor of with Imperius, it's most likely the world had would have been destroyed, on Imperius' insistence.

After the existence of Sanctuary was secured, Tyrael has been was ordered by his fellow angels on many occasions not to interfere with the mortal world. He has often disobeyed, fearing that Sanctuary would otherwise fall in into the hands of the [[Burning Hells]].

When the [[Prime Evil]]s were banished from hell during the [[Dark Exile]], Tyrael helped humanity to create the [[Horadrim]] and creating the [[Soulstone]]s they used to imprison [[Diablo]], [[Mephisto]] and [[Baal]] with, centuries before the events covered in [[Diablo I]] and [[Diablo II]].