Pellatarrum: Dwarf Migrations

Given that the dwarven city-state of Agnakorem is both resource-rich and of infinite height, one wonders why dwarves exist anywhere else. After all, was it not designed to be a dwarven paradise?

It was, but that doesn't mean the residents of heaven are angels. Or, to paraphrase Sartre, "Hell is other dwarves." There are a few reasons for this.

• Dwarf society is extremely conservative. We're talking "1950s America meets the Stepford Wives" conservative. Dwarven society is just so, and it's been that way for millennia, and it works well so there's no reason for anything there to change. If you want things to change, then you're just being selfish -- have you no respect for tradition and heritage? Why do you want to meddle and make things difficult for others?
• Everybody knows everyone else's business. Imagine Agnakorem as an apartment building; specifically, one of those buildings in New York City where bored housewives look out the windows to see who's coming and going, and bored children play on the stoop. Comings and goings are seen, arguments are overheard, new possessions are noticed as they're being brought up the stairs, kids are tattling and adults are gossiping. There is little to no privacy due to the close quarters and the clannish nature of dwarven society, and so anyone who is just a little bit different is noticed and talked about.
• There is a fixed order of doing things and if you don't have seniority, you're on the bottom. Let's say that you're a dwarven craftsman, and you discover a new technique for forging mithril that is faster and easier than the traditional method. Not only will no one else use your new-fangled method -- it isn't tried and true, after all -- but no one else will buy your material, either, because it's clearly shoddy because it isn't properly forged. No one wants to apprentice to you, because you selfishly believe that your idea is better than the wisdom of your ancestors, and so not only are you a disgrace to your clan and your profession, but you also taint everyone who studies under you. Or works with you. Or sells to you. Or is related to you. Or... you get the idea.
  
  The only way a new idea ever gets adopted is if a craftsman submits it to the Council of Smiths, who will carefully look over the proposal and ask questions (like defending your dissertation, only worse), and then if some small glimmer of merit is seen, then a study is commissioned where the long-term impact of your idea is considered. Yes, perhaps you can forge mithril faster, but what will that do the price of mithril? Will the speed of production increase the demand for mithril items? Can the miners meet that supply? Will the increased amount of mithril on the market devalue the commodity? And what about the crafters who make their living forging tools for mithril-workers? Look, there's an entire economic ecosystem here, all very delicate and balanced, and one little change can have catastrophic effects. Let's study it for a century and see what happens -- we don't want to move too quickly now!
• Dwarves live a long time, so you might have to wait decades or longer for things to change. Imagine a family-run corporation where everyone in management is effectively immortal. It's not enough to have merit; you have to wait for an opening. And if people rarely die or get promoted, there's very little room for upward advancement.

So any dwarf who is a little bit different from the norm, or who is nontraditional, or who likes privacy, or wants to try a new technique, or has more ambition than patience is likely to say "Screw this! I'm out of here. I'm going to find my own mineral vein, and set up my own forge/shop/school/colony, and do things my way!" These dwarves are often charismatic and take friends and family with them when they leave. 

This makes everyone happy: disruptive elements are removed from traditional Agnakorem society, and the young dwarves get to do things their own way... until, of course, they become the Council of Smiths, telling upstart dwarves of the next generation to slow down, think things through, and act in the (new) traditional manner. 

And thus the cycle repeats.