Hesduros is a Sangheili colony world. The planet was also part of the Forerunner Ecumene under the name Kelekos. The planet was linked to the Shield World Onyx by a portal system set up by the Forerunners. Huragok maintained the portal on the Onyx side, however the Kelekos side fell into disrepair after the disappearance of the Forerunners.
Hesduros was founded as a Sangheili colony at some point prior to the Human-Covenant war. During the war many young Sangheili from the colony departed to fight in the Covenant military, with very few returning afterward. In the fallout of the Great Schism, Hesduros was largely forgotten. In 2553, Jul 'Mdama escaped captivity on Onyx by fleeing through a portal to Hesduros. Here, Jul met Sangheili from the Panom keep, who were unaware the Human-Covenant war had ended. Jul 'Mdama began to recruit followers of his own on the colony, followers who would later form most of the Sangheili branch of Jul 'Mdama's Covenant.
The Sangheili on Hesduros were highly isolated from political intrigue of the Covenant. Some, such as the members of Panom keep, were resentful of the Covenant religious and military machine, which took far more than it gave to the isolated colonists. As a result, the religious framework of the colonists of Hesduros tended to align more with ancient Sangheili teachings than with more modern San'Shyuum interpretations. When Jul 'Mdama arrived on the colony, he found willing recruits to follow him, promising that the colonists would be subject to neither the San'Shyuum Council nor the Arbiter's new coalition of pro-Human keeps. The backbone of Jul 'Mdama's Covenant was comprised of a new order of Zealots; the Silent Blade, most of whom hailed from Hesduros.
While Sanghelios floundered in the post-war years from a lack of engineers, Hesduros' isolation required that the colonists become skilled engineers for their own survival. Several post-war variants of the Sangheili Combat Harness were adapted and redesigned by Hesduros engineers, most notably the Zealot Harness. Hesduros engineers were also responsible for developing the Harvester, one of the largest Covenant land vehicles ever developed. The engineers of Hesduros were known for their design style, which had a decidedly more organic look than the iridescent purple typical of the rest of the Covenant's designs.