In the ancient Ayurvedic text the Harita Samhita (said to be composed around the 6th or 7th century CE), five different types of mud / clay are described, each with their different therapeutic qualities and distinguishvable by their color: black, red, white, yellow & blue (kṛṣṇa, rakta, sīta, pīta, nīla). The very popular multanni mitti or clay of Multan (also known as Fuller’s Earth) used in cosmetics is one type of white clay. The various clays used in Ayurvedic mud therapy are usually sourced from pristine locations like clean rivers and lakes.