According to Dune, Grumman is the "second planet of Niushe, noted chiefly for the feud of its ruling House (Moritani) with House Ginaz." In the novel, a drunken Duncan Idaho states that his sword was "first blooded on Grumman," killing a Harkonnen in service of Duke Leto Atreides.
The Legends of Dune prequel trilogy relates how the great mercenary Jool Noret is raised here during the Butlerian Jihad.
In Paul of Dune the planet is described as so completely exploited that little exists of commercial value, and the local population barely surviving as nomads wandering between the few areas with remaining resources. The capital fortress of Ritka survives only on food imports from other worlds in exchange for the few minerals that can be extracted from the extensive subterranean mining. Other than base minerals, a local breed of horse is also profitable.
Read more about this topic: List Of Dune Planets