The oldest documents concerning the Holy Blood of Bruges date back to 1256. The Holy Blood probably was part of a group of relics of the Passion of Christ preserved at the Imperial Museum of Bucoleon in Constantinople (modern Istanbul).
In 1203 Constantinople was besieged and conquered by the crusaders. Baldovin IX, Count of Flanders, after being crowned as the new emperor, sent the relic of the Precious Blood to his native country at Bruges.
Recent analyses were made on the crystal bottle containing the Holy Blood. The bottle has been dated as of the 11th century. It is also sure it was made in an area near by Constantinople.
Although in the Bible there is no explicit mention that the Blood of Christ was ever preserved, in one of the Apocryphal Gospels it is narrated that Joseph of Arimathea preserved some drops of the Blood of Christ.
According to an ancient tradition, Count Diederik van den Elzas brought the bottle containing the Blood of Christ from Jerusalem to Bruges during the second crusade. Recent investigations however have pointed out that the relic arrived in Bruges at a later date, probably around 1250 coming from Constantinople.