Minor Factions in the Dune series

Fremen
The Fremen inhabit Arrakis, also known as Dune, the desert planet that is the sole source of the spice melange in the Known Universe.

House of Ix
The Ixians are responsible for providing the technologies for the three Houses to build Missile Tanks and their House-specific vehicles. This is done by building the Ixian Research Facility at the player's base. Once this is done, the player will be able to build either the Atreides Sonic Tank and Ornithopter, the Harkonnen Devastator, or the Ordos Deviator.

Mercenaries
occurrence:

as enemy:harkonnen mission 8

as ally:ordos mission 7,8,9

these are the forces of the ordos and frequently desert.

as enemy,they will help the ordos to attack you.when you capture their heavy factory,they will help you.

as an ally they will help you to defeat the emperor, atreides and the harkonnen.But watch out,they will desert.