The document summarizes the origin and development of international law from antiquity to modern times. It discusses that international law originated thousands of years ago between early political groups and cites examples of treaties between city-states in Mesopotamia from 3100 BC and between Egypt and Cheta from 1400 BC. It then outlines the developments of international legal concepts in ancient Rome, the Middle Ages with the emergence of lex mercatoria and maritime law, and debates around the origin of modern international law from the 9th century onward between Islamic, Christian, and Byzantine empires.