Here's how I beat Dunqul in my ongoing campaign. First, I had something over 25,000 debens in my personal savings. This allowed me to build a lot of important stuff early, and operate at a loss for several years. Second, I played at Normal difficulty. I started in the northern part of the map, and made building infantry my first priority. By the time the Kushites showed up, I had 2.75 infantry co's and 1.5 archer co's. I also buttered up Seth with a temple complex, thus getting his major blessing, where he destroys invaders. The Kushites were pretty easy after this. I can send you a save just before they invade if you want.
Another hint for this map is to send archers around to the various hyena breeding grounds. Once you kill enough off at the breeding grounds, they become extinct. This does not work for most other animals, except (I've heard) lions in Cleo.
Call me Invar, Bugged was a mistake.