The Aztecs dominated Central America for several centuries, from the 1300s to the early 1500s. They ruled at first through a series of alliances . . . in fact the whole empire was at first a series of alliances where in the Aztecs installed friendly leaders in local cities . . . but later through force and fear.
One of their time honored practices saw the Aztecs gathered the severed heads of sacrificial victims, run a small pole through the skulls (horizontally) and set the pole on a post. Each pole carried multiple skulls. These were kept on display for al to see and served as a warning to any who might challenge them of what fate lies before them.
A recent discovery in Mexico has brought all this home again.