In 395 AD, Rome split into two empires - the Western Roman Empire and the Eastern Roman Empire. Each side had a ruler in charge of it. The Roman Empire was split by Theodosius.
The First Geneva Convention (1864) is one of the earliest formulations of international law. International law is the set of rules generally regarded and accepted as binding in relations between states and between nations. It serves as a framework for the practice of stable and organized international relations.
Customary International Law. Customary international law refers to international obligations arising from established state practice, as opposed to obligations arising from formal written international treaties. According to Article 38(1)(b) of the ICJ Statute, customary international law is one of the sources of international law.