After the destruction of the old empire, the Zensunni found Dune. Away from the known worlds, they established their own secluded society on Arrakis. Here their culture adapted to the unrelenting environment.
Underneath their decorated armor the Zensunni would wear an Aljulud Althaanui, which translates to "secondary skin". This complex body suit was used to survive the harsh climate. Many of its features have been adopted by modern stillsuits.
Garments like these were made of hide and even human skin, as these are the few materials available on Arrakis. The Zensunni found it honorable to be turned into an Aljulud Althaanui, since their remnants would benefit their kin after death.