The peace treaty of Kadesh. From the Wikipedia: The Kadesh peace agreement—on display at the Istanbul Archaeology Museum—is believed to be the earliest example of any written international agreement of any kind; and “The battle [between the forces of the Egyptian Empire under Ramesses II and the Hittite Empire under Muwatalli II at the city of Kadesh on the Orontes River, in what is now Syria] is generally dated to 1274 BC”