According to Wikipedia:  The earliest recorded evidence of the production of soap-like materials dates back to around 2800 BC in Ancient Babylon.[5] In the reign of Nabonidus (556–539 BCE) a recipe for soap consisted of uhulu [ashes], cypress [oil] and sesame [seed oil] "for washing the stones for the servant girls".[6] A formula for soap consisting of water, alkali, and cassia oil was written on a Babylonian clay tablet around 2200 BC.