How did they make they buffalo fat into soap?

Buffalo fat, also known as tallow, is rendered by heating the fat to separate it from any impurities and water. Once rendered, the fat is combined with an alkali, such as lye, in a process called saponification, where the fat reacts chemically to form soap and glycerin. The mixture is then poured into molds and left to cool and harden. After curing for several weeks, the soap is ready for use.