The Midlands

The major roads of the Midlands primarily consist of Blue Highways. Worlds in the Midlands are beyond the control of the Highland Parliament. The Grand Postal Service does not deliver there, though private express package services connect some of the worlds. Interstellar polities of various sizes and government types exist there. The road networks tend to be held by either private companies, which generally means they are toll roads, or by local governments. Intersection portals tend to tie together systems owned by others, sometimes for tolls, sometimes just to skim what they can off the transshipping traffic. Transmat portal networks are few and far between. Those that do exist tend to be larger commercial units, rather than personnel doorways.
Though the Midlands are beyond the reach of the Highland government it is not beyond the reach of the Church. Many monasteries, convents, hospitals, missions and banks belonging to the Church knits together the Midlands more tightly than if they were not there. The Church maintains its own courier service and transports pilgrims great distances.
Much of the area of the Midlands is only accessible using B/G engines configured for travel off the road network. System beacons guide ships from great distances, though some still get lost. Still some hardy souls run transport trains along the Blue Highways and stages between the other systems.
Without the Pax Terra These governments do sometimes wage war, though rules about damaging gates and subspace superstructure are fairly well followed. There aren't enough hyperspacial drills and beacon portal manufacturing facilities for governments to frivolously destroy those that do exist.
The Grand Human Union is civilization. Every year the Highland Department of Roads spreads Blue Highways and Major Routes farther out, connecting worlds at the Highland border to worlds beyond. Every year the justice of the Highland Rangers and the power of the Star Legion moves farther away from the capital/center of the Highlands, encroaching on the Midlands. Worlds that resist are bypassed, to wither in economic isolation. Worlds that embrace the advancement win seats in the Grand Parliament.
Some flee, further into the Midlands and eventually into the Wilds.