Those then who, in Persia and elsewhere in the world of Islam, devoted themselves to the practice and dissemination of ascetical and mystical doctrine soon became known as ‘Ṣūfis’, a name given them because, as we saw, they chose to wear a distinguishing dress of coarse, undyed wool (ṣūf), a type of dress already worn by Christian ascetes in the East. Later on, this habit was in general replaced by the khirqa, or patched frock, which was given by the Pir or sheikh to the novice whom he accepted as his disciple (murid).