The Arelonian Empire
The west and east of Leng are divided, physically and culturally, by vast expanses of wilderness. Nowhere is this divide more apparent than in the naval superpower of Arelon. It is not the oldest surviving civilisation on Leng - Caragoth, its capital, was built 50 years after Antiras, the oldest city on the continent - but the Arelonians are nonetheless an ancient and civilised people. They worship a pantheon separate from both the old gods of Leng and the Trinity, which they believe was brought to them from the Otherworld by Emperor Numa I who bears the blood of Vulcan. Every Emperor since has been counted a demigod in his own right.
The Arelonian Empire, once a superpower that seemed like it would never end, is now dwindling. It is ancient and decadent. Once both Astinus and Agatea were mere Provinces of the Imperium, but by 250 BE both had seceded in an event that would come to be known as the "Great Rebellion".
The reason that Arelon lost its southern provinces is the same thing that has vexed Arelon almost since its founding: The Sea of Pearls. The Arelonians are a naval people, with the mightiest fleet on all of Leng. Yet almost all of their attentions are turned westwards, to the lucrative shores of that great ocean. Yet it was more than the reckoned for: it was mercenaries and privateers from the Sea of Pearls, after all, that Agatea hired to protect itself. Even hundreds of years later, controlling and policing the Sea of Pearls take up a majority of Arelon's resources - though they profit greatly from it.