The Galaxy is divided into four segments: The Alpha Quadrant, the Beta Quadrant, the Gamma Quadrant and the Delta Quadrant. The Federation are located in the Alpha Quadrant whereas the Borg inhabit the Delta Quadrant. So far, the Delta Quadrant has only really been mapped by the USS Voyager, which took a mere peek at the inner workings of that Sector, whereas the Alpha Quadrant was almost entirely mapped by the USS Enterprise.
This Galaxy is considered one of the League's best outposts for trade and military strength, however, the appearance of the Borg is considered an annoyance. The Technologically advanced Humans here are the remnants of the original Human Empire, segments of which fled to the Trek Galaxy to escape war with the Flood and the Forerunners, which saved them from the Halo Array and allowed their society to continue - hence why they have such advanced technologies whilst their counterparts in the Milky Way languished in pre-industrial sqalour for 102,000 years thanks to the idiocy of the Forerunners.