Genghis Khan was a bit more ruthless with his methods, he invented “measuring against the linchpin”:
“All male captives were forced to walk beside a wagon wheel. If their heads were higher than the linchpin (a pin inserted at the end of the axle) they were immediately executed... This technique was probably used to preempt against revenge attacks that were common between tribes at this time. If one tribe were to attack another, there was always the possibility that there would be a revenge attack soon after. By eliminating the older males, there was less chance of a counterattack from tribes that were in perpetual conflict due to centuries of distrust and robbery.”
Or the Bible, where every person that pisseth against the wall was killed.