The inhabitants of Cervan.
An avian species, the Cervantes used to be all alike physically but due to the introduction of banishment to the night side as a punishment thousands of years ago, two species have evolved.
The Cervantes on the night side, who retain the name Cervantes, resemble humanoid versions of a have two birdlike claws for feet and even have a long thin tail. They have semitransparent wings and have a head shaped similarly to that of a terrestrial feline with feathers strangely enough.
They have arms that are more like claws attached to the end of their wings, which they can fold down when not in flight. Their feathers are normally a similar red to their sky with some variations. They can live to over 50 terrestrial years old.
The night side Cervantes, called the Ervyncis, are similar in appearance to the Cervantes only their head is shaped more like that of an owl than a feline. They have thick fur underneath their thick feathers and have evolved bio luminescence which helps them see as well as keeps them warm.
Their feathers and fur are black in visible light and they can see in infrared. While they can see visible light an amount like that from their parent star is enough to make them go blind fast.
The first Cevantes appeared near one of the western seas near the ice shelf over two million years ago. They moved around, looking for places to settle down until they found a perfect place to do so. There they began building a small civilization there. As it grew some left to find other fertile lands. The first expeditions towards the sun returned with tales of how the sun seemed to rise as they traveled and of strange animals and plants as well as rising temperatures.
Other expeditions headed north or south. They saw that the plants and animals changed as well but the sun moved a different direction. Their scholars deduced from this early on that they lived on a sphere. Curious as to what would happen when the sun went below the horizon they attempted a journey west. They barely made it back alive with tales of strange lights in the sky and a cold that rivaled anything they’d felt. They realized that they lived in a comfortable zone and expanded into it only.
Over hundreds of thousands of years they slowly expanded, slowly growing in number as they could only have offspring once in their lives and that was usually only two. A million years ago there was a massive religious war among those of one side of the planet with those of the other. This drastically diminished the global population and caused a collapse in most major civilizations.
From this a group of highly religious zealots arose. Taking advantage of the fear of the general population, they spread their beliefs around. Anyone who they found to be impure they exiled to the dark side, never to return. These crusades against the so called heretics lasted for many years until the last of the rebels were purged. They set up a theocracy all around the inhabitable area and a new age began.
The Cervantes on the other side of the planet began to use their own slightly better scientific advances to try and survive in their new dark and cold environments, practicing a primitive form of genetic engineering to slowly create the current subspecies of Cervantes. They called themselves the Ervyncis after the ancient demons of the day side religion. Soon they began to even believe that they were in fact actual demons. The endless cold war between them has lasted ever since, each side preying on the other.
Currently the global population is 109 million, 54 million Cervantes and 65 million Ervyncis.
Once a society of free thinkers, the Cervantes, both subspecies, have become extremely religious, each side believing in ancient gods that are constantly at war with each other.
The Cervantes have a theocracy with a capital near their first ancient cities on the day side which they believe is where their gods arose before the creation of the heavens. The king is also the religious leader of the people, something like a planetary pope. He has absolute authority.
The Ervyncis have little in way of a central government, opting instead to run wild as they please, acting by feeling alone, making them unpredictable. They prey on those who wander to far darkside.