Were there any civilizations that did not have a class system?

While most known civilizations developed some form of social hierarchy, there are a few examples of societies that operated with minimal class distinctions. Hunter-gatherer groups, for instance, often exhibited egalitarian structures with shared resources and decision-making. Additionally, some small-scale tribal societies may have had less rigid social stratification compared to larger, more complex societies. However, as populations grew and civilizations became more complex, class systems typically emerged.