Translatio sanguinis Domini

[2] According to the Translatio, Azan, the prefect of Jerusalem, having heard about Charlemagnes virtues, miracles and victories in battle, wishes to see the emperor in person and sign a treaty of friendship.

He approaches Pope Leo III to arrange a meeting, offering Charlemagne "gifts greater than anything ever before brought to the West", but the emperor rejects the overture.

The pope, who understands that it is relics of Jesus that are in view, sends messengers to the emperor, saying, "if ... you are proclaimed as the most famous in the whole universe, you ought to give your life over to danger, if the situation demands it, and walk on foot after him to procure so magnificent a treasure."

In the guise of a pilgrim, Charlemagne walks barefoot from Ravenna to Sicily, where he finally meets Azan and receives the relics in an onyx reliquary.

The character of Azan is based on Hassan, the real Muslim prefect of Huesca, who sent Charlemagne tribute in 799, according to the Royal Frankish Annals.