The earliest known use of a natural, soap-like material was the powder of nuts from the Reeta (Sapindus) tree, a powder used by Indians since antiquity. In accordance with Ayurvedicteachings, Hindus in India were obliged to bathe at least once a day, every morning.The Babylonians used clay cylinders containing a soap-like substance, dating from 2800 B.C.E. A formula for soap-consisting of water, alkali, and cassia oil-was written on a Babylonian clay tablet around 2200 B.C.E.The Ebers papyrus (Egypt, 1550 B.C.E.) indicates that ancient Egyptians bathed regularly and combined animal and vegetable oils with alkaline salts to create a soap-like substance. Egyptian documents mention that a soap-like substance was used in the preparation of wool for weaving.It has been reported that a factory producing soap-like substances was found in the ruins of Pompeii (C.E. 79). However, this report appears to be a misinterpretation of the survival of some soapy mineral substance, probably soapstone, at the Fullonica where it was used for dressing recently cleansed textiles. The ancient Romans were generally ignorant of soap's detergent properties and made use of the strigil to scrape dirt and sweat from the body.The word "soap" (Latin sapo) appears first in a European language in Pliny the Elder's Historia Naturalis, which discusses the manufacture of soap from tallow and ashes, but the only use he mentions for it is as a pomade for hair. He mentions rather disapprovingly that among the Gauls and Germans, men are likelier to use it than women. According to one legend, "soap" takes its name from a "Mount Sapo" where ancient Romans sacrificed animals. Rain would send a mix of animal tallow and wood ash down the mountain and into the clay soil on the banks of the Tiber. Eventually, women noticed that it was easier to clean clothes with this "soap." The location of Mount Sapo is unknown, as is the source of the "ancient Roman legend" to which this tale is typically credited.In fact, the Latin word sapo simply means "soap." Borrowed from a Celtic or Germanic language, the term is cognate with the Latin term sebum(meaning "tallow"), which appears in Pliny the Elder's account. Roman animal sacrifices usually burned only the bones and inedible entrails of the sacrificed animals; edible meat and fat from the sacrifices were taken by humans. Under such circumstances, animal sacrifices would not have included enough fat to make much soap. The legend about Mount Sapo is probably apocryphal.A twelfth-century Islamic document describes the process of soap production. It mentions the key ingredient, alkali, which later becomes crucial to modern chemistry, derived from al-qaly or "ashes".By the thirteenth century, the manufacture of soap in the Islamic world had become virtually industrialized, with sources in Nablus, Fes, Damascus, and Aleppo. Soapmakers in Naples were members of a guild in the late sixth century (then under the control of the Eastern Roman Empire), and in the eighth century, soap-making was well known in Italy and Spain. The lands of Medieval Spain were a leading soapmaker by 800, and soapmaking began in the Kingdom of England about 1200. Castile soap, made from olive oil, was produced in Europe as early as the sixteenth century.In modern times, the use of soap has become universal in industrialized nations due to a better understanding of the role of hygiene in reducing the population size of pathogenic microorganisms. Manufactured bar soaps first became available in the late nineteenth century, and advertising campaigns in Europe and the United States helped to increase popular awareness of the relationship between cleanliness and health. By the 1950s, soap had gained public acceptance as an instrument of personal hygiene.