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 within the religious tradition of Bon. In Bon, shamanistic Bonpo used primary-colored plain flags in Tibet. Traditional prayer flags include woodblock-printed text and images. History 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 Bhikṣu 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. During the Cultural Revolution, prayer flags were discouraged but not entirely eliminated. Many traditional designs may have been lost. Currently, different styles of prayer flags can be seen all across the Tibetan region. Lung ta/Darchog styles There are two kinds of prayer flags: horizontal ones, called Lung ta (Wylie: rlung-rta, meaning "Wind Horse" in Tibetan), and vertical ones, called Darchog (Wylie: dar-lcog, meaning "flagstaff"). Lung ta (horizontal) prayer flags are of square or rectangular shape, and are connected along their top edges to a long string or thread. They are commonly hung on a diagonal line from high to low between two objects (e.g., a rock and the top of a pole) in high places such as the tops of temples, monasteries, stupas, and mountain passes. Darchog (vertical) prayer flags are usually large single rectangles attached to poles along their vertical edge. Darchog are commonly planted in the ground, mountains, cairns, and on rooftops, and are iconographically and symbolically related to the Dhvaja. Color and order Traditionally, prayer flags come in sets of five. The five colors represent the five elements and the Five Pure Lights. Different elements are associated with different colors for specific traditions, purposes and sadhana. Blue symbolizes the sky and space, white symbolizes the air and wind, red symbolizes fire, green symbolizes water, and yellow symbolizes earth.