It is within the nature of mankind for a disproportionately small percentage of men to attempt to exert control over the greater multidinous horde. The primary method of control is achieved through violent oppression.
Violence is required as most people will not willingly submit to control by others, be it few or many. For violence to be perpetrated, weapons are required. Our history as a species can be defined, in large measure, by the vehicles of violence (weapons) employed at the point in history being addressed.