[...] Parallels with viking raids immediately come to mind. "From the fury of the Northmen, O Lord, deliver us." Or the Huns. "The Scourge of God." Raiding warriors being seen by their opponents and demons in human guise does have plenty of precedent. [...]
Thinking on this subject some more, I remembered a super evocative phrase that the Byzantine historian Jordanes used to describe Scandia (the Romans' name for Scandinavia, which they mistakenly believed was an island).
He called it "
The Womb of Nations," which evokes the unknown, a mysterious place where many strange and hostile peoples apparently come from. But, because Europe is big, travel is hard, and knowledge often fails to be transmitted into durable written records, there can be all kinds of people out in the distant north that are barely known or understood.
But the first time I heard the phrase was in
Hardcore History's Death Throes of the Republic series, in which the Romans are blindsided by an army of Cimbri, i.e. giant* shirtless Danes. Because without satelite communications, its really easy for a massive army to show up at your doorstep without much warning--and for you to not really know where they came from or why they're attacking you.
*giant to the Romans, anyway, who were 5' to 5'5''
So considering this:
Remember that 1e FR population densities are extremely low. The average Orc probably never encounters any of the 1e sedentary/PC races. When they do, they go kill-burn-pillage. But that's just what the PC races experience vis-a-vis Orcs. 99.9% of the time, Orcs are not pillaging human villages. They probably never encounter a human village.
And that the 1e Forgotten Realms are stupidly gobsmackingly large.
(source, forgotten realms camapaign setting, DM sourcebook p. 10...
why on Earth did you need so much space Ed?)
Maybe there are all kinds of orc and goblinoid civilizations thriving throughout the savage frontier. Perhaps they have all kinds of complicated political interrelationships; sometimes weaker groups are displaced and put into conflict with demihumans, sometimes there are big wierd confederations to accomplish various ends--which would explain why orcs, goblins, ogres, etc. always end up together in a team.
Or maybe said orc/goblin civilizations are only doing ok... or even quite badly. Ancient Jutland wasn't wildly populous, and the Cimbri were purportedly displaced by flooding (
no one really knows), but they nonetheless raided and sacked their way through western Europe beating consular armies of 80,000.
(from
Wikipedia)
If your average dwarf hold has a population of something like 10ish thousand, that kind of horde would certainly give them a rough time.
I really quite do like the suggestion that someone made that Gruumsh is not just a distant creator god and mythological figure, but an active despot who really wants the claim of being lord over a powerful people of strong conquerors. No matter how many orcs have to die for his dream. We do have plenty of examples of purely mortal human dictators doing just that and somehow getting a large majority to be full on board or at least going along without protesting.
Add to that an army of religious police shamans and the whole lunacy of it all becomes pretty realistic. We do see dissent in real countries. But if you have something like this going for thousands of years and hundreds of generations, and the eternal war with the hated mortal enemy is not just propaganda but nearly constant active warfare, then it becomes fairly plausible that barely anyone considers that society is total madness and pointless suffering.
Dear Leader Kim Jong-Gruumsh.
Taking the Womb of Nations idea a step further, it could be a real phenomena that intermittently pops out big groups of orcs. What if there's a series of portals to Gruumsh's divine domain--or maybe his wandering interplanar army; at some point the orcs didn't have a divine domain. Gruumsh occasionally sends one of the tribes that serves him in the afterlife to round up all his minions in FR and do some damage. This would partly explain their lawful orientation, since it'd be a army with military discipline and organization. It would also explain their servility to Gruumsh, since his threat of force is always there. They'd obviously pop out in one or more of the mountain ranges--spine of the world, ice mountains, or greypeak mountains--which would explain their longstanding beef with the dwarves.
---
OR
Maybe don't decide what's going on with the orcs, but try to make it a mystery (i.e. make them a
/sigh mystery box). There are tough organized raiders who
it is said destroyed the dwarves and elves in ages past, and who are known to unexpectedly form invasion armies, but who come from an unknown homeland, and have unclear motivations. You can have the evil marauding humanoids, but throw in unexpected signs of greater complexity when the PCs interact with them. Then you listen to the players speculate about them and steal liberally when/if they have good ideas.
Eh, maybe that's a difficult lift given how done to death the evil orc horde archetype is.