United nomad tribes before the attack on the capital in the climax of the story. Although technologically outmatched by the Empress, nomads are able to equal the terms of engagement. Large Monsoons, serpent-like creatures from the far reaches of the Outer Lands, are armored and used both, as a troops transportation and a weapon. Though they are pretty slow and are not particularly dangerous by themselves (apart from their sheer size), augmented with the hoover-engines, they can be used very efficiently as a 'living hovercrafts' and rams. Floating above the ground allows nomads to steer them over sharp rocky terrains that normally keep Monsoons at bay. Smaller units, called Zephyrs, are used typically for combat. These are fully mechanical, usually composed from elements coming from Desert Trains and shot down Frigates.
And some initial roughs: