Typhon sector

From Memory Alpha, the free Star Trek reference

The Typhon sector is an area of space within Federation borders.

In 2373, this sector was the rendezvous point for a Starfleet task force led by Vice Admiral Hayes, and the location of the initial engagement with a Borg cube en route to Earth. The fleet failed to stop the cube in the sector and fought it all the way to Sector 001. (Star Trek: First Contact)

The Typhon sector may be somehow related to the Typhon Expanse of TNG: "Cause and Effect".