How and why do historians believe slavery started?

The precise beginning of slavery is difficult to track because its origins predate historical recording and the written word. Due to the sociological makeup of the groups, we know that slavery wasn’t a part of hunter-gatherer societies, so the first identifiable evidence of slavery comes from the Code of Hammurabi out of Mesopotamia. This ancient text refers to slavery as a common practice throughout the region which had been in place for thousands of years at the time it was written.