Also, interesting power dynamics are possible. Oftentimes the ERE would go to war or launch raids against territories that were nominally theirs, or at least owed them fealty.
So to start introducing this idea, we can use a bog-standard traditional fantasy world, with kings, dukes, etc. An expeditionary force from the Eastern Empire marches across the plains, their arms and armor of strange make, their customs and appearance alien. Their general Theodoric the Orc calls on various kings and dukes to remind them of oaths of fealty and suzerainty made years ago. The kings are not happy to be reminded.
The force was meant to march west, receive the barbarous forces of their allies and subjects, and march northeast to open a new front in the ongoing war between the Empire and the Enemy. However, the various dukes and kings are finding reasons to delay their entry into a costly foreign war. The glittering troops of the Empire have bogged down in a camp outside the capital, and as delays continue tensions are mounting. The army was meant to receive part of their pay as plunder, and the bored, underpaid soldiers are starting to eye the wealth and resources of the area. The kings are starting to wonder if this glittering Empire they've never seen ought to ruling over them.



















