Random Civilization Name Generator

Civilizations are almost never named by the people living in them. "Sumer" comes from the Akkadian word for the region, "Aztec" was popularised by later scholars, and "Byzantine" was invented a century after the empire fell. Most names we use come from four sources: a founding people or tribe (Assyrian, Mongol, Norse), a ruling dynasty (Han, Tang, Ottoman after Osman), a capital city or river (Babylonian, Indus Valley, Great Zimbabwe), or a form of government (the Roman Republic, the Achaemenid Empire, the Aztec Triple Alliance).

Those same patterns make invented civilizations sound real. A people-name plus a political noun (Vaelorian Hegemony, Talvaran Confederacy) reads as a scholar's label. A dynasty name (the Ondrathi Dynasty, the Amber Dynasty) suggests a long history with rulers who could be listed. A geographic name (the Reef Cities, the Salt Kingdoms, the Riverine Cities of Ur-Kalath) tells you where the culture lives and what it depends on. A descriptive epithet (the Drowned Empire, the Sea Peoples of Kadran) sounds like a name given by frightened neighbours, which is often exactly the tone you want.

When you choose one, decide whether the name is what the civilization calls itself or what outsiders call it, and use both in your world; the gap between the two is a story in itself.