Following the binding of the Overlords by the Silver Flame, the remaining fiends withdrew to the Demon Wastes and the ancient city of Ashtakala to regroup and recover. Here, they began to scheme and lay the groundwork for their millennia long schemes to free their masters. These fiends formed the Lords of Dust, a loose alliance of rakshasa and other fiends working towards similar goals: the release of the Overlords.
The Lords of Dust have quite possibly infiltrated every organisation in Eberron. Rakshasa are spirits of deception, and they masterful infiltrators and manipulators. They have been manipulating events in the world for as long as there was a world to manipulate, and they are patient. They are immortal and time doesn't hold the same significance to us that it does to them, so a rakshasa agent is more than happy to spend possibly several human lifetimes deep undercover.
The Lords of Dust are led by the Bleak Council of Ashtakala, a group of approximately 90 fiends, many of which are the prakhutu to one of the overlords. Below these are the Claws of Khyber, fiendish agents that act as the council's claws out in the world, who do most of the active field work for the Lords of Dust. Below these, the Lords of Dust manipulate thousands of pawns, mortals from all walks of life, most of whom will never know who their actions serve, or even that they are working to someone else's agenda at all.
The Lords of Dust are a loose alliance between the forces of the various Overlords, rather than an effort to collaborate on a larger scale. The release of an Overlord requires careful manipulation of the Draconic Prophecy, and some prophetic paths that lead to the release of one Overlord will actually block the release of another. Primarily, the Lords of Dust serve as a way for the rakshasa to share resources and avoid unintentionally interfering in each others plans.