Eruption of the Deep Roads

Geological / environmental event

A hole ripped open on Ersia, right in the middle of Chirider. From the chasm spewed forth hundreds of thousands of denizens from the Deep Roads - the most terrifying of which were the Fraelings.

Fraelings were expanding territory aggressively. The conflict was pushing populations in the Deep Roads closer and closer to the surface. It is said a creature cast a powerful spell that set off a chain reaction leading to a massive implosion in the surface. As the dust settled and earth caved in, both sides had access to each other like never before. Instead of small caves and tunnel systems big enough for small groups leading to the surface, there was now a massive hole through which armies could travel.   Much of the differences between the Deep Roads and the surface populations were quickly evident, however. Because of the topology of the Deep Roads, armies weren't effective. That was on top of the fact that governance was either nonexistent or wildly different from the governments and bureaucracy of the surface populations. It looked much more like a mass migration than anything. In response, the Chirider armies marched inwards from the edges of the empire. Though asymmetrical, favoring the Chirider armies in many ways, their lack of information and coordination lead to their crushing defeat.   While most people from the Deep Roads had trouble adapting to life on the surface, fraeling did not take long. Their incredible power and access to new, abundant sources of nutrients gave them many advantages. They also stood and fought the Chirider armies while most other fled or scattered. All of this combined to make fraelings the dominant species and began a golden age, from their new, elevated, perspective.