The Empire of Nerath was founded about 1400 years ago as the Kingdom of Nerath on the island of Silenus off the south coast of the sub-continent of Adan in the Azure Sea. The Kingdom of Nerath was a maritime power, trading all over the Azure Sea. They spread civilization wherever they went, and erected many temples to their godless of civilization, Erathis. The sub-continent of Adan was mostly howling wilderness, and they went about taming it, creating settlement after settlement.
About 1100 years ago, war erupted between Nerath and the city-state of Argoth. Argoth was located on the northern tip of the continent of Kadith, the southern shore of the Azure Sea and was once a trading partner with Nerath. The new Tyrant of Argoth, entertained imperial ambitions, and built a massive fleet, sending his Lord Marshal to invade Silenus
The attack was brutal and caught the legions of Nerath by surprise. The Lord Marshal’s armies sacked and burned at will. The King of Nerath himself led four legions against the enemy, but his army was crushed and the king killed. The Lord Marshal went on to besiege Ardane the capital of the Kingdom of Nerath.
Before Ardane was besieged though, a courier managed to get out to take a message to general Lucius Marius Aurelius, a brilliant tactician and cousin to the king. General Aurelius was in western Adan with a bare two legions, and rushed to the defense of Ardane.
That night, a priest of the fledgling Luminarian faith came to general Aurelius and blessed him. That night Aurelius dreamed of a banner bearing the solar cross symbol of the Luminarian religion, blazing with a blinding light and leading him to victory. Before the break of dawn he went to the priest, and as the sun rose over the camp, he converted to Luminarianism.
What followed is a tale of military genius that is still taught in military academies to this day. With his two legions, some 10,000 men, Aurelius took out an army that outnumbered them five to one. He first burned the enemy’s fleet then roused the countryside and split his legions into their individual cohorts to harry the enemy.
General Aurelius broke the siege of Ardane, then routed the Lord Marshal’s armies. He followed the invaders to the sea where they found their escape cut off. The legions of Nerath crushed the invading army, killing them to a man. The Lord Marshal fell on his own sword.
A year later General Aurelius led an expedition against Argoth itself. The city was razed and burned, and the Tyrant captured and beheaded. On his return to Ardane with the head of the former Tyrant on a pike fixed to his chariot, General Aurelius was crowned Emperor Aurelius the first of the Empire of Nerath. This was deemed as Year 1 of the Imperial Calendar.
The Empire expanded made further inroads into Adan after that, reaching to the furthest corners. Although primarily human, the Imperial communities were made up of all the civilized races: Deva, Dragonborn, Dwarf, Eladrin, Elf, Genasi, Halfling, Half-Elf, Human, and Tiefling.
The Empire of Nerath lasted for approximately 600 years after that, succumbing finally to combination of corruption, as cults of Tiamat and Asmodeus took hold, and multiple invasions by savage humanoids.