A Tibetan prayer flag is a colorful rectangular cloth, often found strung along trails and peaks high in the Himalayas. They are used to bless the surrounding countryside and for other purposes. Prayer flags are believed to have originated with Bon. In Bon, shamanistic Bonpo used primary-colored plain flags in Tibet. Traditional prayer flags include woodblock-printed text and images.
Nepal Sutras, originally written on cloth banners, were transmitted to other regions of the world as prayer flags. Legend ascribes the origin of the prayer flag to the Gautama Buddha, whose prayers were written on battle flags used by the devas against their adversaries, the asuras. The legend may have given the Indian bhikku a reason for carrying the heavenly banner as a way of signifying his commitment to ahimsa. This knowledge was carried into Tibet by 800 CE, and the actual flags were introduced no later than 1040 CE, where they were further modified. The Indian monk Atisha (980–1054 CE) introduced the Indian practice of printing on cloth prayer flags to Tibet and Nepal.