The Great Plains was once host to a large variety of nomadic tribes, consisting of mostly hunters and animal herders. The Plains are notably ill-suited for farming, save for around riverbeds. When the tribes started to linger around said rivers and streams, merges began to take place and societies sprung up. By the estimated middle of the Territorial Era, the Sadahn Sultanate had been well-established. It existed with a rigid caste system, in which upward mobility was nearly unheard of.
For a time, the Sultan was viewed as the greatest generals of their time, able to stave off attacks and claim new territory alike. By the beginning of the Three Kingdoms Era, however, it had started its slow decline. Sultans became seen less as warriors, and more like pampered children. While a competent ruler would come around every so often, most of the major decisions were made at the behest of greedy viziers and ministers.
This weak government is seen as the primary reason they were able to fall so swiftly to the Empire, with the royal city of Shiyah falling in 813 GWE.