I think you need evidence of a system of government, agriculture, culture, laws to dispense justice predictably and a writing system to track and record aspects of the above. Hence we can have Egyptian, Indus, etc., but not prehistoric civilizations. The human organizations just didn’t have enough progress to be considered civilized. Thats not to say they were not advanced vis a vis their other contemporaries but rather didn’t meet certain milestones that mark a civilization.