The Calesian Sector is an area of space about 100 light years in radius situated within the Amatria galaxy and under the superior control from the Calesian Empire since 11196 CE. It surrounds the system containing the E-Class planet Calesius.
Since formation of the sector, the Calesian Empire has managed to retain control for thousands of years, except for a few major conflict periods between 17000 and 23000 CE.
By the the year 11985, the sector became infested with the Amatrian Galactic Spherium's interstellar probes when the two civilisations made contact, but the Empire refused to accept the Spherium's offer to join the government; when military tensions between the civilisations began to rapidly rise. It would be the root cause of the Fourth Amatrian War.
Fortunately for the Empire, they managed to expand their influence sphere radius by another 900 light years, and further increasing the military tensions against the Spherium.