In the tunnel, Daryl finds drawings of a crowning of what appears like a king, and other scenes. I wonder if these drawings indicate that at some point someone appointed himself as a king in the DC area, and what else these images tell us about what happened there.

It's quite obvious to me that the group entrenched there early in the apocalypse, otherwise they would not have packs of dollars.

 

Looking at the drawings again, it appears like they tell the story of a struggle between a group that wore crowns and another group, over food.

 

I'm less inclined toward complex interpretations. If it was the commonwealth, you would have seen direct references, and not hints.