By the year 4583 BA, Gliat Shea had expanded to encompass most of the known world at the time in a series of conflicts called the War for Prorh, Prorh being the old Gliat Shean name for the world. For the next 5000 years approximately, Gliat Shea ruled the known world in an age of prosperity, but by the year 418 AA, this would all come tumbling down. In 418 AA, a civil war broke out after the Emperor died without appointing an heir. While there had been civil wars for this same reason before, none were as large as this one. The Emperor's 6 sons all rallied different parts of the Empire to their cause, and with the nation split into 6, the 6 sons all declared war on each other to reunify the Empire with them as the Emperor. Instead of ending in a few short years as expected, the war lasted for over 200 years, with the 6 sides of the war having been brought down to only 3. These 3 signed a peace treaty in the year 691 AA, with the Emperors of all 3 nations ruling as co-rulers. Finally, Gliat Shea has been united again.
However, the civil war had a major toll on Gliat Shea. Over the years, surrounding nations and tribes had been taking advantage of the conflict and nibbling at the borders. By the time the civil war was over, Gliat Shea was only 1/3rd of its original size. Another result of this was the downturn in the Gliat Shean economy and its military strength. Previously, its army and economy had been the greatest in the known world, but by the end, it was military weak and its economy was in shambles. It got so bad that widespread famines became a common occurrence, and countless revolts by the peasantry also became common.
By the mid-to-late 730s though, Gliat Shea was on the verge of collapsing. The nobility, which had once been complacent, was now on the verge of revolt. Before any revolts by the nobility could happen though, the Emperor, Arpad XXXIV, did a mass purge of the nobility in 734 AA and took away the large majority of their power, as well as exiling vast amounts of nobles. Among these nobles were the Harstads, previously Grand Dukes of Brudal in northern Gliat Shea, and arguably the most influential noble family at the time.
While the exiled nobles traveled in all directions, the majority of them went east, where they thought that they would be safe from Gliat Shea. By 736 AA, the nobles that went east finally arrived in Asendavia and established their own small communities across the country. By 780 AA, these communities had become full fledged city-states. For a little over 80 years, life continued like this, with each city-state shrinking and growing in power, and occasionally going to war with each other. The only thing that unified these city-states were their belief in Ademar and the God-on-Urth.
In 864 AA, the then-current monarch of Stromharad, Adelar III of house Harstad, seeking to gain immense amounts of power, claimed that he was a descendant of Ademar and claimed dominion over the surrounding city-states via divine right, and one by one, they fell before him. However, he died suddenly in 908 AA, cutting his conquests short. By this time though, the majority of southeastern Asendavia was already his. Adelar III's son, Hjalmar II, would complete his father's conquest of southeastern Asendavia in 923 AA. Now styling himself as King of Stromharad, Hjalmar II set his eyes on the island of Yoria. This conquest would last until 927 AA, when the last lord of Yoria, Terje V, surrendered to Hjalmar. Like his father though, Hjalmar II would also die a sudden death, likely caused by poison. By the beginning of 928 AA, the Kingdoms of Tungrad and Zhelelovka, north and northeast of Stromharad respectively, would conquer the last of the independent city-states in Asendavia east of the Ademarite Mountains.
In 931 AA, Ademar IV, the son of Hjalmar II, declared war on the much weaker Kingdom of Tungrad. However, the King of Zhelelovka was threatened by this, as he had also wanted Tungrad's land, and he felt threatened by the Kingdom of Stromharad's rapid expansion. As a result, the King of Zhelelovka declared war on the Kingdom of Tungrad and the Kingdom of Stromharad, officially beginning the conflict known as the War of the Kingdoms, which would last for over 500 years. Rather than only actually being one war though, the conflict was actually a series of wars. Notable battles of the war include the Battle of Fagergrund, which was fought in the town of the same name between all three kingdoms and is remembered as the most deadly battle in medieval Asendavia; the Battle of Brekstrand, where the Kingdom of Zhelelovka attempted to invade Yoria and failed; and the Battle of Skoggrund, where the king of Stromharad, Viktor III, slew the king of Tungrad and his heir.