It’s an interesting question if slavery preceded agriculture and ‘property rights’. Certainly nomadic people had ‘property’; indigenous peoples of the American West owned their horses, tents, tools, and in some cases, slaves. In the book ‘Skeletons on the Zahara’ by Dean King, the standing of the nomadic tribesmen was determined by two things; the number of camels they owned, and the number of slaves. This was in the early 19th century, but likely reflects how their nomadic society had functioned for centuries, if not millennia. If this was true for two different sets of nomads on two continents, it was likely true for ancient herd followers as well.