Believed to be descended from hounds once kept at the Abbey of Saint-Hubert, Belgium, it is known to French speakers as the Chien de Saint-Hubert. This breed is famed for its ability to discern human scent over great distances, even days later. Its extraordinarily keen sense of smell is combined with a strong and tenacious tracking instinct, producing the ideal scent hound, and it is used by police and law enforcement all over the world to track escaped prisoners, missing people, and lost pets. In the 16th century, John Caius, in the most important single source in the history of the Bloodhound, describes its hanging ears and lips, its use in game parks to follow the scent of blood, which gives it its name, its ability to track thieves and poachers by their foot scent, how it casts if it has lost the scent when thieves cross water, and its use on the Scottish borders to track cross-border raiders, known as Border Reivers.