The kingdoms and empires only hired Pagna warriors to help with certain issues that arose, but there had always been an agreement to keep matters separate between them.
To keep regular people out of the world of Pagna warriors. This, in a way, gave freedom to both tiers of citizens.
Those who accepted themselves as Pagna warriors could face each other and follow the rules of the warrior. Being a warrior meant understanding the risks, and those not wishing to get involved could stay separate.
It wasn't as if regular people didn't have things to worry about, and kingdoms, empires, and such continued to fight against each other anyway.
One aspect that the kingdoms were building on was knights. Knights who wore specially crafted armor on their bodies, designed to be impenetrable to a sword.
In many ways, some thought it might be a secret weapon against the Pagna warriors if a fight ever did break out between the two groups.