The Par'tha Expanse contains about 70 systems and a large number of temperate worlds. Many of these worlds have been heavily settled. Other systems also have settlements, but much smaller ones: research stations, military outposts, mining facilities, and so on. There are two distinct parts to the Par'tha Expanse: the Expanse Sector and the Freeworlds Region. In the Expanse Sector, the Caraadians are the dominant species, and any indigenous races are treated as second-class. In the Freeworlds, though Caraadians are numerous, indigenous races have more freedoms and rights, and are able to rule their own worlds...to a certain extent.
That certain extent would be the will of the Valcarian Imperial Republic. The Empire conquered the Par'tha Expanse with little or no effort, due to the rapid surrender of the Par'tha Expanse Great Council. The Empire currently allows the Expanse to run itself, as long as they follow Valcarian laws. As a reminder, Valcarian military units and vessels can be found throughout the Expanse.