Ancient Egypt was the first country to be united under a single government and culture, establishing the concept of a nation-state. Its geography, isolated by deserts and waterways, helped foster a unified culture. The annual flooding of the Nile River allowed Egypt to develop a large, centralized population and surplus agriculture. This led to the rise of powerful pharaohs who ruled as divine kings and directed labor toward massive construction projects like the pyramids. The strict social hierarchy and religious beliefs centered on Ra and Osiris helped maintain political and social stability in Ancient Egypt.