To provide an extremely brief overview that does not do the saponification process justice: When fats or oils come into contact with an alkali, they are broken down into fatty acids and glycerine, which then combine with the sodium or potassium component of the alkali. Excavations in Ancient Babylon unearthed a soap-like material produced by a process consistent with this, namely boiling fats with ashes, according to accompanying inscriptions. Similarly, the Ebers papyrus, dated 1550 BCE, reveals that Ancient Egyptians washed with a mixture of animal and plant oils and alkaline salt, while the Chinese, during the Zhou Dynasty (c. 700-221 BCE), mixed plant ash with crushed seashells to produce an alkaline chemical used for staining.