 Why does the Viceroy want to overthrow the Sundans?
The sight of an Earthman on Vega III, where it was impossible for an outlander to be, brought angry crowds to surround John Crownwall as he strode toward the palace of Viceroy Tronn Ffallk, ruler of Sector XII of the Universal Holy Empire of Sunda. If they carried out the threats of their present attitude, Earth would have to send Marshall to replace him. A pair of guards, their purple hides smoothly polished and gleaming with oil, crossed their ceremonial pikes in front of him as he approached the entrance. "If you mean His Effulgence, Right Hand of the Glorious Emperor, Hereditary Ruler of the Seventy Suns, Viceroy of the Twelfth Sector of the Universal Holy Empire"—Universal Galactic had a full measure of ceremonial words—"he sees only those whom he summons. "Just tell him that a man has arrived from Earth to talk to him. An elegant courtier, with elaborately jeweled harness, bustled from inside the palace, obviously trying to present an air of strolling nonchalance. His Effulgence commands you to appear before him at once." "It's customary to genuflect when you enter the Viceroy's presence," said the standing one at last. "It was only decided yesterday, back on Earth, that I would be the one to make the trip here. What I meant was that I expected someone from Earth to break through our blockade and come here. "If you wanted someone from Earth to come here to see you, why did you put the cordon around Earth? And why did you drop a planet-buster in the Pacific Ocean, and tell us that it was triggered to go off if we tried to use the distorter drive? "We offer you partnership with us to take over the rule of the Galaxy from the Sunda—the so-called Master Race." "I'm Viceroy of one of the hundred Sectors of the Empire. I rule over a total of a hundred Satrapies; these average about a hundred Provinces each. There are more inhabited planets in the Galaxy than there are people on your single world. I, personally, rule three hundred trillion people, half of them of my own race. There was even serious discussion of destroying Earth out of hand, while it is still possible. While these creatures could by no means be classed among the intelligent races, there was a general expectation, which we reported to the Sunda, that they would some day come to be numbered among the Servants of the Emperor.
 The Vegans were around before the Sundans, therefore the Vegans should be in charge of the galaxy.
 The Sundans do not understand polite society or etiquette. They really must be stopped.  The Sundans are waging war on the Vegans.  The Sundans are a race of brutal warriors, oppressing everyone in the galaxy.  The Vegans were around before the Sundans, therefore the Vegans should be in charge of the galaxy.