The kingdom became as a single city, Stofstans. The first king was Ayst Inst an Stofstans. The city always dominated the immediately surrounding countryside, but outward expansion began in earnest during the reign of Ijermeshil I (1088-1121).
From that time on, the rulers of Stofstans undertook an overtly nationalistic program to unite all Stofonians under their rule. Once this had largely been accomplished (the original Stofonian homeland of Aksurst remained part of the Elosian Empire), they turned their attention to the neighboring Custs, and eventually the Mayols and Maaldobs across the Sea of Elos.
Probably the most far-flung territory was Knarr, which "purchased" from the Elosians in 1340.
In 1349, the Elosian Empire fell to the Vians, Tigils and Ertcils. King Rostof I proclaimed that Stofonia was now "the" Empire (Elikaln), implying that there was only room for one single great empire in the world, and the fall of the Elosians left a vacuum that the Stofonians were now ready to fill. Thus began the Stofonian Empire.
Form of Government
It is difficult to say whether this "kingdom" would be categorized as a monarchy or as a dictatorship if it had existed in Europe. The kingship was not neccessarily hereditary; the king was free to appoint any successor he chose. On the other hand, most of the time they actually did choose their own son or other close relative.
In order to prevent confusion and chaos in the event of a king's sudden death (which was likely, considering that kings routinely lead their troops into battle), the next-in-line for the throne was always publicly announced by the king early in his reign. This was done via the unusual Stofonian Succession Ceremony.
There was initially very little hint of "nobility" or "artistocracy" about the Stofonian government. The king was first and foremost a military leader, and his power was based on the strength of the standing army. The army itself was an almost shockingly un-medieval organization. There were no social classes in the army. Men of the poorest backgrounds routinely rose to high ranks of the army, and were subsequently appointed to important government offices, some even becoming kings.
Slowly but seemingly inevitably, however, a new hereditary elite arose. While theoretically every person in the government served at the pleasure of the king, many offices gradually became pseudo-hereditary after the manner of the kingship itself.
The Stofonians from the time of Ijermeshiel benefitted from better swords than their enemies. While most were fighting with swords that were at best a very weak steel, the Stofs had discovered techniques that produced much harder weapons that kept their edge.
The final days of the kingdom saw the introduction of gunpowder into the Stofonians' world. It was initially obtained from the Gulluainians, but the Stofonians rapidly put it to much more extensive use.