The Circassians were originally Kobolian colonists who settled on the planet of Caprica. Circassia was not an individual tribe, but rather a group of Capricans who believed in certain beliefs and thoughts that conflicted with most other tribes. The Circassian movement was a militaristic one that longed for an empire that spanned the stars... but the democratic colonists could never understand that longing.
The Circassians and Capricans went through a series of wars throughout the history of settlement days. A separate language developed for the Circassians... and their numbers grew by three-fold. At the outbreak of the First Planet War, Capricans numbered 400 million while Circassians numbered 260 million.
The war was devastating to both sides, and afterwards only 40 million Circassians were left... most children and old men. The survivors used what technology they could to build primative colony ships to flee to another planet in the solar system.
The colony ships were nightmares, poor technology and poor navigational systems caused many of the ships to either explode or to drift lost in space. Only a few of the original ships made it to a new homeworld..... one far from the colonies.... far from any known sapient race...
The new homeworld was a huge, beautiful, peaceful planet. The remaining colonists quickly built cities and populated the planet. Scientific research multiplied and new techologies allowed the Circassians to colonize several planets nearby... instigating the Circassian Empire.
This Empire grew in strength and encountered many new species and incorporated them into the growing empire. Warships were built to protect and defend the empire. Shortly after the Colonial holocaust, First Contact occured between the Battlestar Athenia and the Circassian Battlecruiser Revenge. The contact ignited a small war in which the colonials attacked and won the planet of Dacia. The planet of Lycia, a Circassian outer capital, revolted against Circassian rule and opted to join the Colonial government.... bringing 6 billion humans into the colonial fold.
At the moment, there is a small truce between the Colonies and the Circassian Empire.
The population of some of the more advanced planets within the empire are:
Circassia: 14.5 Billion
Eleria: 13.5 Billion
Alcacia: 8.4 Billion
Circadia: 5.4 Billion
Jjoodi: 3.5 Billion
Karala: 2.1 Billion
The total population of the Circassian Empire is over 78 Billion inhabitants, humans make up 67% of the total population.