Ipyr was a lush, green world; and the primary home-world of House Thorvald, which governed the planet as an Earldom in the Landsraad. During to the first rebellion against Emperor Paul Atreides Muad'Dib, from 10,194 AG to 10,198 AG; led by planetary ruler Memnon Thorvald, the planet was Thorvald's base of operations.

When Paul Atreides discovered Thorvald's intent to devastate the Atreides planet of Caladan, he forces the Spacing Guild? to eject Thorvald and his followers into deep space and leave them to die.

Paul Atreides's forces then "sterilize" Ipyr, using "weapons, explosives, highly toxic chemical bombs, defoliants, and wide-dispersal incendiaries" to destroy every living thing and render the planet uninhabitable.

Sources: Paul of Dune?,

On the net: Dune wikia,