The Fall of the late Natin Empire in 300 A.D paved the way for the Germans in Northern Araseos and Scandinavia to migrate to Northern Nonscio, while most chose to settle close to the ruins of the once-proud Empire, some travelled even farther to the fertile southern flatlands of Aldenbourg. A few decades later after they settled, some of the Germanic peoples of southern Aldenbourg went further north, hoping to find more arable land, although when they arrived they only witnessed large mountains, cold weather, and a hefty amount of snow. The harsh weather and mountainous landscape did not deter them however, so they settled, although because of this their culture changed drastically; some reject agriculture and chose to pillage the southern settlements as it was considered the new way of living.

In the 400s AD, most of southern Aldenbourg was settled by great kingdoms, duchies, and counties. These states would discover the feudal system and many implemented it in their way of life. Feudalism would be common until in the 1500s when it was considered inhumane and cruel. Great lords and kings would either abuse or care for their subjects, although most chose the former. During this era, the kingdoms of Bavasia, the Sturggen, and Aldenbourg were considered the most powerful, although, the kingdom ruled by the Aldenbourgians would prevail.

The Aldenbourgians/Aldenbourgers descended from the settlers that chose to pillage neighbouring states, during this period of Aldenbourgian history they would conquer the lesser states that surrounded them, as is the way of surviving during this era. They effectively conquered all of Aldenbourg in the 1000s due to their crueller nature, although eventually they would adopt the Christian faith and chose not to fight or subjugate but to defend and care. The Knights of the Eisenordnung of the Aldenbourgian Kingdom were considered one of the best warriors in the early history of Aldenbourg.

The Bavasians were a race of proud people that hailed from the southern parts of today's State of Bavasia. The Bavasians were the first group of Germans in the region to adopt the Christian faith and believed they were destined to conquer most of medieval Aldenbourg. They descended from the settlers that chose to farm, and so they had a relatively large population during the era. Their military was not to be underestimated though, because of the large population they organised a large yet unprofessional, conscript army. They managed to repel the Aldenbourgian skirmishes but, however, during the Aldenbourgian Invasions of the 1200s, they were soundly defeated.

The Sturggen were the earliest settlers of Aldenbourg, they settled the southern coastal area of Aldenbourg in the 290s AD. They were a primarily maritime culture and traded with various states that settled near the Piscary Sea, they controlled the Dübenz River, which was considered vital to the Sturggen peoples. The Sturggen kingdom was rich due to their commerce and was one the greatest kingdoms of medieval Aldenbourg until it was invaded by the northerners in the 1100s.

Pagan religions were common during this era since it was passed down by the heretic Germans in the 300s. The Bavasian Kingdom, however, was the first group of peoples to convert to Christianity. Originally they adopted Levantine Christianity but reformed the religion a bit and created Bavasian Christianity, which was less conservative by their standards.

The Aldenbourgians of the north descended from the Germanic settlers that moved further north and founded the Aldenbourgian Landgraviate, the legendary Eroberer House would rule this mighty kingdom until in 1783 when the last king died without an heir. For reasons unknown, the king was not permitted to pass the crown to his siblings, cousins, or close relatives. The Aldenbourgians were considered savages and pagans by the Bavasian kingdom of the south, while the northerners believed the Bavasians were cowards and traitors of traditional Germanic rituals. The Aldenbourgians would nonetheless convert to Christianity. Over the course of at least two centuries, the Aldenbourgians, through means of ruthlessness and malevolence, managed to conquer most of the region. The Bavasians managed to repel most attacks, the Sturggen and most lesser states did not stand a chance.

After subjugating the Sturggen, Bavasians, and other peoples, they eventually converted to Bavasian Christianity which was renamed to the Kirche des Königs and after centuries, in 2030, Dermont would rename it as Aldenbourgian Christianity. The small Islamic minority from Unistan were largely oppressed.

The number of coasts acquired by the Aldenbourgians was disappointing, they tried to push westwards but failed. After countless failed invasions of the west, they eventually gave up.

The north was a frigid, cold, desolate place filled to the brim with mountains. However, most Aldenbourgian kings believed behind them was fertile land with an abundant amount of gold. Eroberer kings sent countless expeditions to the north, most never came back, although, those who did had no gold or silver in their pockets. The kings were persistent and continued to send expeditions, until 1390 when they stopped and eventually they realised it was not worth it. A couple of centuries later these expeditions would continue, although, they did not come for gold but for oil and land.

The Aldenbourgian populace rumoured of gold and silver in the Southwest, and the government was interested. The first expedition was commanded by King Georg II in 1399, he was killed, however. After the king was killed, the kingdom vowed not to send any more expeditions. Until on 1587, when an explorer, Gerhard von Nitzer, came back with gold and silver. The kingdom continued to send the expeditions and eventually drove out the nomads. They later annexed it.

Since 400, Feudalism had been a way of life in Aldenbourg since the Eroberers ruled the nation. However, after the last Eroberer king died without an heir, the current government created the Elector Senate, a powerful institution meant to elect kings and/or pass new laws. The Elector Senate's first decree was to abolish Feudalism, as it was cruel and inhumane. And the descendants of serfs and peasants were given money as compensation. For now, Aldenbourg was an elective monarchy and not a hereditary one. This institution, however, was plagued with corruption. The first elected king ruled for 70 years and forced the Elector Senate to extend the term length to 60 years. Almost all of the elected kings were nobles instead of common folk, although, this did not bother the populace as they witnessed hundreds of centuries being ruled by an all-powerful king.

In the 1700s and 1800s, Aldenbourg witnessed a golden age, even greater than the golden age brought by past Eroberer kings. The currency was more valuable, industrialisation began, and the military grew. Overall, it was a good time to be alive in Aldenbourg.