The Treaty of Kadesh 13th century BC
The Treaty of Kadesh, concluded between Pharaoh Ramses II of Egypt and Hattusili III of the Hittite Empire, is widely regarded as the earliest known written peace treaty in history. It represents a foundational moment in the development of diplomatic practice and international legal agreements. A replica of the treaty is displayed at the headquarters of the United Nations as a symbol of peace and diplomacy.
Reference:
United Nations – Replica of the Treaty of Kadesh
https://www.un.org/ungifts/replica-peace-treaty-between-hattusilis-and-ramses-ii