The main enemies of Blackmoor were the Egg of Coot and the Temple of the Frog, creations of Arneson and his players alone. But there was another group that could go back to the Domesday Book. Domesday Book #9 establishes an enemy of the Great Kingdom called the Paynim Kingdom. Few details are given on the Paynim Kingdom except that they have a strength of 150% of any of the other kings of the Great Kingdom. Paynim, apparently is a term used in medieval literature to describe Islamic antagonists during the Crusades.
Originally, I thought that references to the Paynim could also include the Peshwa, but I now suspect this is not the case. Greyhawk still has its Plains of the Paymin, but in Blackmoor I suspect that the Paynim evolved into the Afridhi. The FFC mentions The Treasure of the Paynim Princess*. I now believe that the Paynim Princess could be no other than Toska Rusa.
*=Actually the text in the FFC says "Treasure of the Payme Princess" which could be either a typo or a pun.
|How I imagine Toska Rusa, Queen of Afridhi, Mistress of Zugzul.|
I have previously discussed how the Afridhi as they became known were further fleshed out when one of MAR Barker's friends took on the role as the Afridhi Queen. This could have been the time when Dave Arneson invented the God Zugzul, patron of the Afridhi. These nomadic invaders were even further fleshed out in DA4 where they are the main antagonists of the adventure, seeking the mysterious Well of Souls. David Ritchie's wife is attributed to providing more detail on Afridhi culture. So even though alot was changed over the years, the Afridhi could have seen their first little spark in the Domesday Book.
Image Source: Nomad Warrior, by N*Deed
Image Source: Barbarian Chick, by Maciej Kuciara