Prior to the arrival of Imperial Starfleet, Bolarus and it inhabitants were almost always in a state of constant warfare. The early Bolian clans fought for territory, while centuries later, cities conquered one another or came together to form nation states. At the time of imperial conquest, in 2246, the Bolians were divided into three superpowers, the Bol'se, Bol'ki and Bol'ra nation-states.
When Starfleet arrived at Bolarus, the planet and its three nations had just about recovered from a fourth world war which had been fought with nuclear and biogenic weapons. Recovery from the war took seven centuries, during which time the Bolians developed sophisticated technologies to reclaim their planet's irradiated surface, cure mutagenic plagues, and repair the protective atmospheric layers.
It was Robert April of the ISS Enterprise who ultimately led the empire's invasion of Bolarus. Each of the three nations offered their allegiance to the empire in return for destroying the other two. April made promises to all three nations, and, when ready, betrayed them by destroying 97% of the Bolian fleet. Colonial administrators arrived shortly thereafter and stripped the authority of each nation's governments down to only ceremonial powers. By the height of the empire, administrators were harvesting the planet's resources and enslaving Bolians from all three nations. Surprisingly most Bolians did not direct their anger towards the empire, but, instead, their rival nations. Each would send representatives to colonial administrators hoping to garner some small favor against the other two nations.
Nevertheless, there were a few Bolians who recognized the absurdity of their planet's outdated nationalistic sentiments. The Bolian Resistance, led by Darthalo the Knife, called upon the planet's population to overthrow the empire and conquer the galaxy for themselves. Through the murder of Terrans and the sabotage of installations, the resistance waged its own war against their oppressors. (Decipher RPG module: Through a Glass, Darkly)
Following the victory of the Terran Rebellion and its allies over the Klingon-Cardassian Alliance in January 2379, the Bolians joined the newly formed Galactic Commonwealth. Its representative to the Commonwealth Assembly was Min Zife. (ST - Mirror Universe novel: Rise Like Lions)