Reaper also has a good collection of Arabian types, including a good selection of mounted models.
My first warband used a bunch of Darkest Africa, Pirate and Indian Mutiny figures from Foundry. Pricey now, wasn't too cheap then...
In addition a search for Armies of Araby or similar should find several good conversions for Warhammer Fantasy Araby armies using High Elf and or Bretonnian Men at Arms plastic sets.