The area of space known as the Horuulis Expanse was always of interest to Starfleet and the United Federation of Planets due to the tales of unexplored planets and systems inhabited with sentient life, including that of some warp capable societies. However, due to the lack of relationships allowing transport through the territory of the Talarians and Tzenkethi, they were unable to access the area. The region of space between the Tzenkethi and Breen, however, provided a natural corridor due to gravimetric storms and other spatial phenomenon rendering the area too hazardous to travel.
In 2390, the storms seemed to have disappeared and space travel seemed possible through the corridor between Federation territory and the Horuulis Expanse to the Tzenkethi and Breen territories. Starfleet sent a vessel to investigate and they determined that the area was indeed safe for space travel. When they began to journey further into the corridor to chart it their vessel was attacked by an unknown group of vessels and retreated.
A second attempt was made by Starfleet in 2391 to send another vessel into the Expanse, however, contact was lost with the vessel. In the aftermath of the loss of the USS Yorktown, the second vessel to enter the expanse operations within the area were canceled by Starfleet Command.
Between the desire to explore the expanse and the threat that these new hostile entities provided, the Federation Council tasked Starfleet with the exploration of the corridor, the expanse, and securing the Federation Border Starfleet Command issued orders to Task Force 39’s Commanding Officer, Vice Admiral Brianna Avery, to establish operations within the expanse and corridor.
In our current year, 2394, the Task Force now fully operational within the Area of Operations.