What is going on with these dwarfs? How do they have so many armies so cheap?

Karaz-a-Karak, with 20 settlements, has 17 full armies, and that's just those I can see. Looking at their armies, they seem to have crazy upkeep reductions: longbeards are only 25 gold, gyrobombers only 63, etc. Each stack seems to be around 1000 gold total. I'm playing on hard campaign difficulty, which I know reduces AI upkeep, but other factions aren't nearly that bad. I've never played dwarfs before, is this something they can legitimately do?