"History's Lost Empires" refers to powerful civilizations that once thrived but eventually fell into decline or disappeared. Examples include the Maya, known for their advanced knowledge in astronomy and mathematics, and the Roman Empire, which dominated much of Europe before its fragmentation. These empires left behind significant archaeological sites and artifacts that provide insight into their cultures. The reasons for their decline vary, including factors like war, disease, and environmental changes. The Inca Empire in South America, for instance, faced challenges from Spanish conquest and internal strife. Studying these lost empires helps historians understand the complexities of human societies and their legacies.