To study history artifacts are needed and often they are lost to history because they have been buried and not found, are under water, are broken or ruined in some way, the site has been raided by thieves and items taken, war often interrupts digs or the archeological sites are destroyed by armies and information is lost. These are just a few things that makes it hard to study early humans and things are found all the time that historians learn from.
Historians need good sources (preferably, written sources) on which to base their studies. If early societies did not leave any written information , historians have to go by other indications like the remnants of villages and temples and perhaps some drawings or carvings. Sometimes these give an indication how societies were (or might have been) organized, but without written confirmation you can never be completely sure. so is that help full or not