The Kahun Papyrus (~1850 BC), the oldest known gynecological treatise, describes pessaries made from mixtures of honey, natron, and crocodile dung inserted vaginally. The Ebers Papyrus (~1550 BC) expands these formulas with acacia, whose fermentation produces lactic acid — a genuine spermicide — and whose tannins have experimentally verified spermicidal activity. These are the earliest records of deliberate technical contraception in documented history.