The Skeksis, also known by themselves as the Arakkoa, are an ancient, brilliant, imperialistic, and arrogant race of avian humanoid creatures originating on the continent of Arak in Velous. The Skeksis were one of the oldest mortal civilizations on Earth, next to the Elves. Arguably one of the strongest races on Earth, the Skeksis have since fallen from their golden age, and have gone into obscurity.
They rose to power immediately after the Fall of the Dragons, and began an aggressive campaign of expansion across the planet, known as the Skeksis Wars. They destroyed everything that stood in their way for around a hundred and twenty years, until they were pushed off of Terra by the Macedonians under the command of King Antroklis the Bright Helmeted. Their Empire eventually came to an end in the late 4th century, and they were forced to return to their homeland.
In terms of warfare, the skeksis have both warriors and magi, which used their vast magical power to forge many arcane technologies for war, such as giant magical suits of living armor known as Garthim, which acted as their servants and military. The races that they enslaved also became their servants as well.
The Skeksis were the sole cause for the collapse of the Ancient Elven Empires, the Ancient Egyptian Empire, and the Ancient Greek Empire. It is believed by historians that the Skeksis would have conquered the entire planet were it not for King Antroklis of Macedon. However, the Skeksis are reclusive now, and their homeland of Arak is a place of great mystery to this day, and Skeksis are very rarely seen outside of Arak nowadays.
Since the Skeksis are such an ancient race, predating humanity and nearly coming into existence alongside the elves, Skeksis history is mostly the stuff of mythology.
In Skeksis legends, it is said that during the waking days of Earth, a great raven-god named Tash descended from the heavens and poured out his breath onto the barren lands of ancient Arak. The raven-god's breath seeped into the soil of the land, and gave rise to mighty forests. Next, Tash spilled some of his own blood onto the newly born land. The dust of the land mixed with his blood, which created the first Skeksis, which Tash named the "Arakkoa" (children of Arak). The raven-god then returned to the heavens, allowing his creation to live on their own.
It's said in the Skeksis legends that in the millenia after Tash's departure, their population continued increasing, and they thrived. However, later on, several Skeksis priests arose, each with different ideas of how to glorify Tash, and some even claimed to have the direct word of Tash. These priests gained many followers, and over time, grew more and more distant from each other. Eventually, the priests divided completely from each other, forming nine great kingdoms of the Skeksis, each separate from the other. The priests grew gluttonous with power, and became seen as gods. In what culminated as the War for Arak, the nine priests made war against each other, each attempting to seize the land of Arak for themselves. The land was devastated, and many lives were lost. It seemed that the Skeksis would surely wipe themselves out from existence.
However, a lone Skeksis appeared on the scene, one who vowed to end the war, and to restore the Skeksis people to their former glory. His name was Terokk, a brilliant and mighty warrior who seemingly came from nowhere; literally no one knew who he was prior to his rise. Terokk traveled the lands of Arak, slaying the nine priests as he went and preaching about unity and the power of the Skeksis people. The people of Arak gravitated to him and became his followers. Eventually, he was able to reunite the Skeksis people, and formed the first Skeksis Empire. Terokk came through on his promise; his people rose to great heights, going through a renaissance and revolution of culture and technology, and great wealth spread across the land. The lands of Arak were transformed, great palaces and structures were built in honor of Terokk, who they now believed to be the second coming of Tash. Terokk even called the nine children of the priests of the past kingdoms, and called them to serve his empire. They agreed, and formed the first Imperial Council. Since then, the legends say, the descendants of Terokk have ruled the lands of Arak.