When the Persian army invaded Alamut, Princess Tamina entrusted Asoka with the duty of taking the Dagger of Time out of the city to safety. During the battle, he ran into Dastan and risked his life in a fight to keep the dagger from Dastan. Dastan defeated him and took the blade. Whether or not Asoka was killed at the time was never shown.
When events are reset by the Grand Rewind, he is standing behind Princess Tamina with his arm in a sling, indicating that he was injured in his battle with Dastan and not killed.