Tion, sometimes also referred to as Tion Proper, is the planet that had been originally settled by the first Humans, who had arrived from the Core aboard their legendary sleeper ships in what would later become known as the Tion Cluster. It is this cold, oceanic world that is the historic cradle of Tionese civilization and society and the cultural heart of the surrounding interstellar region. Most of Tion’s surface is covered in deep blue oceans that harbour a variety of aquatic life, with the most notable being an endemic subspecies of the cy'een that developed a thick, blubbery hide over the aeons to better withstand the cold waters. Yet, the planet’s surface has several stretches of icy glaciers that have grown wide and deep enough to serve as anchors for the cities and settlements that arose around them. Over time, these metropolises became home to millions, and later billions, of Tionese, who eventually settled the stars of the Tion Cluster, laying the groundwork for many star states that would emerge in this interstellar neighbourhood.

Before the formation of the Galactic Republic, Tion had been one of the member worlds of the Kingdom of Cron until it was absorbed into Xim the Despot’s empire during his grand conquest of the Tion Cluster. Upon Xim’s death and the fall of his empire, the planet regained its independence when it formed the Honourable Union of Desevro & Tion as a successor state and went through a period of vast growth and prosperity in the millennia that followed. Eventually, the Union of Desevro & Tion became a member state of the Galactic Republic when the entire Tion Cluster entered its embrace.

Yet, during the Clone Wars, Tion had grown dissatisfied with its membership in the Republic, as much of the Tion Cluster had become a quiet galactic backwater during the region's millennia-long affiliation with it. As a result, the planet had seceded from the Republic during the Clone Wars and aspired to regain much of its political weight and influence over the Tion Cluster as a member of the Confederacy of Independent Systems. However, this did not occur until many decades later, when the Tion Hegemony was reformed and the planet Tion was absorbed within its borders. Today, the world is the centrepiece jewel of the crown of Tionese worlds that have come under the control of the reformed Hegemony.