That must be from some super early version of the mod.
The later versions (as well as the future proper release for Warband) features the invaders as The Empire, themed after romans, invading with as much as 20k (!) or more troops
Maybe I'm thinking of a different mod then. Hmm..
Regardless, the black army scared me more than the Empire ever did in SoD. They had far more numbers but they died easily enough. I could cleave through with brute force. The black army just stood there shooting me while my men died in droves then charged to kill the men that just spawned in to replace the men that died. I had to headshot their archers twice let alone their actual melee soldiers.
Unfortunately I liked SoD far better but it had issues with my computer. I had problems with battles and it would either lag heavily or freeze sporadically. Not fun. I liked the idea back in the original M&B and liked the new map they made for warband. Unfortunately I couldn't handle it or it was too buggy. Either way..