An Inheritance of Stars
Mankind has been spreading across the Argylian Expanse for hundreds of generations since the Fall. During this time, much has been lost. For example, since the Fall, the knowledge of how to use a black hole as a Warp Gate has been lost. During that dark time, mankind effectively slid hundreds of years backward technologically. However, when humanity arrived in the Argylian Expanse, they were still in possession of advanced knowledge and tech. Secrets such as Hyperspace travel, and Warp Gate creation were preserved thus allowing mankind to begin rebuilding anew.
Many of the original worlds first colonized maintained their knowledge, and were able to colonize and rebuild into an advanced lifestyle without much difficulty. Colonies established later would not have the same level of support, and unless buoyed by trade or immediate value to their Parent Star System, would inevitably face a backwards technological shift. This fall in tech level could last anywhere from four to forty (approx) generations before the colonized world could rebuild to the point of its habitation. In some unfortunate cases, circumstances were such as to drive their colonies almost back to the stone age.