The Rotakan Empire is a world-spanning empire that operates as the unifying government for the Rotakan world. If propaganda were to be believed, it has always existed. As much propaganda does, this lie contains a certain kernel of truth. The Rotakan Empire has only existed in its current form for about 1500 years. However, before the empire existed an empire called the Rotakan empire. The Empire goes through iterations every few thousand years (soft average), where it will be overthrown only to re-establish itself as another Rotakan Empire under new management. To date, no one has overthrown the empire in order to remove it and virtually no one know when the first empire was actually established or how. A single unifying government has existed for so long it may not even occur to the Rotakan people that another was is even possible. Instead, the Empire is overthrown mostly because some province (or alliance of provinces) believe they have a better way to run the empire.
The latest iteration overthrew the prior empire by establishing a propaganda machine among the provinces that turned the people away from the Empire. It also made a liberal use of assassins to thin out the power structure. It was not hard. That prior empire had emphasized freedom and technology with little oversight. By the time of the overthrow, most of the power had consolidated into the hands of a select few that hoarded it over the rest. Poverty was rampant and hunger was literally the number one cause of death.
The new Empire established a completely different paradigm. It solidified a provincial structure that had decayed under the old empire, establishing Royals to govern and manage each province. It outlawed most gravtech in an effort to maintain control and prevent any one individual or group from attaining too much power. Godlings were hunted and killed for the same reason. The new empire also established slavery as an integral part of the government's penal system. All prisons were removed and convicts were shipped off to Ionia to work in a newly minted food program the government created. Ionia, until then, had been mostly a curiosity. Only the rich would go there and usually not for long, given it was a desert planet. Most new you could grow food there, but there was little incentive as the sheer effort it took was simply too great. The new empire changed this paradigm. Slave labor is cheap, and they used that labor to grow food. Eventually, the empire's food production grew so prevalent and cheap that it started driving other producers out of business. Several hundred years after it's establishment, the empire delivered its coup de grace and made all of its food production completely free to all citizens of the empire. It was a masterful move. Criminals were literally removed from the planet and instead of draining resources were used to generate food instead. Once the empire's slave-generated food was made free, it solidified the system. No one could justify moving against 'slavery' when it was only the criminals who were made slaves. No one wanted to bite the hand that fed it.
The free food also gave the empire an iron grip on the provinces they'd 'created' (in truth these provinces existed but closer to city-states at the time). No province could move against the Empire without alienating their own people, who depended on the food the empire provided them. The Empire also conscripted soldiers from each province into the Empire's army making it virtually impossible for any one province to field anything close to what the empire had on standby. Of course, the Empire had a solution to that as well: war.
War was a government sactioned event in the Empire. War had, of course, always been present no matter what form the Empire took. Early iterations of the empire had attempted to rid itself of war but somehow that only built pressure instead, often resulting in a world-wide revolt. The current iteration took a different approach and made war integral to the Empire. With provinces now being ruled by families of Royals, the empire decided to codify the standard for war. By decree, no provincial land ownership could change hands unless it was freely given or else won during a government sanctioned war. Any province that attempted war without a War Writ would find themselves facing off against the empire itself with devastating consequences. The only time this happened the province that dared ended up half its size on half rations for a decade. It never truly recovered and continues to serve as a warning to other Royals.
A war writ lasted a year, to provide both sides the time they needed to resolve their conflict. The Empire was very free with its war writs, seeming to only avoid them if too many wars were being fought at once. Indeed, the Empire seemed to encourage conflict among the Royals by throwing bi-yearly provincial parties where all provinces were invited. These parties actually carried a fatality rate due to assissanations, duels and other intrigue among the Royals and inevitably sparked a war or two.
The common people were generally left out of the political intrigue but the Empire had setup certain protections to prevent abuse. Any citizen was free to live where ever they wanted and no Royal could prevent them. Royals could also move out of their province but would become common citizenry at that point, which rarely happened. Royals who abused their citizens soon found themselves with no citizens, no money and no power. With food being free over the entire empire, the barrier to moving was lower to commoners. This provided an incentive for Royals to at least treat their citizens decently. Of course, some do better than others.