The Orcs unite under a single leader and conquer all civilized lands...

The Orcs unite under a single leader and conquer all civilized lands. What would happen here over the course of the next 100 years?

Basically Shrek 4.

Well, half orcs are going to become a lot more common.

It depends whether your orcs are capable of being non-evil or not. If they aren't, near total destruction of civilisation, slavery and horror abound, things are utterly fucked.

If they are capable of being non-evil, the new regime will likely be harsh and militaristic but, in the way almost all conquerors do, they'll be influenced by the local population and culture, as well as practical necessities, into becoming at the very worst a neutral governing body. You'll likely see orcs marrying into a lot of noble families, creating half-orc royal bloodlines to retain legitimacy in the eyes of the populace while also cementing the orcs place as the dominant force in society.

>If they aren't, near total destruction of civilisation, slavery and horror abound, things are utterly fucked.
So basically Belgian rule in Congo. But the Belgians had a home-state where life was good for them.

Depends...
If you are going by Tolkiens orc, then it would be a rapid industrialization and tyranny, maybe a genocide or two

Not exactly

Depends on the setting

Look at Yuan China or the Seljuk Empire. Or the Merovingians.

>tolkien third age orcs
That's fairly close to the scouring of the shire, but I could also see Sauron and Saruman just exterminating populations that pose a real threat to their rule. Saruman's voice could sway men into working for him, and Sauron could keep the peoples of the east as his allies so long as they were useful. Hobbits wouldn't be seen as a threat worthy of thorough extermination, but I don't see elves lasting long under bad-guy rule.

It would be really ugly and awful, but ironically technology would advance. Saruman would likely bring his black powder, industry, and likely other marvels into prominence. I don't know if he'd figure out primitive firearms or grenades, or if he'd just stick to using his powder for siege weapons.

They become a ruling class, but over generations they'll start assimilating to the conquered culture, although remnants of Orcish culture will remain among the higher castes for generations to come.

Which is more or less what always happens when a nomadic/barbarian group conquers civilized lands and settles there as rulers.

...

The empire would fracture immediately after the death of its leader and over time come crashing down, similar to the Mongols.

Vaguely what the Muslims did during the days of the Umayyad Caliphate: some backwards desert dwellers conquered two highly advanced empire that had exhausted themselves against eachother. The result was that due the imposition of the Jizya, the new Muslim upper class was able to get filthy rich.

I imagine orcs would be somewhat the same, but with less religious justification (unless you want them to, or if you follow Robert Spencer's theory where Muhammad and Islam were invented post-facto to justify the conquests). They become the new ruling class and allow humans, elves etc. to do what they do best (being civilized) as long as they're heavily taxed if not downright enslaved.

Ghengis Khan split his kingdom between his children before his death.

and they crashed down with no survivors

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Your thinking the Macedonians.

Way more orc posters.

>Marching his army through a desert, killing thousands of his men, just to prove that he's better than Cyrus
>His empire collapses instantly, unlike the legacy of Cyrus
He had it coming.

Less orc threads, more dwarf threads

I think this was the case in the Shadow of the Demon Lord setting, where the orc slaves rose up and took over the empire.

Something something orc dick, something something snu snu

They will eventually break their unifiezation.
I mean, without outsider threats they would collapse under internal conflicts.

Sauron didn't like orcs. They were a useful tool in subjugating enemy kingdoms, but there's a reason all of his high ranked servants outside the ringwraiths were humans, and that one of his titles he wanted was Lord of Men.

He probably would have started pogroms and camps to kill off the orcs if he had won.