This includes the one world (at 1718) that did have a minor race who are now extinct.
You mean the Kachiya. Their system is a M-class binary, standard/tainted atmosphere, medium-sized / 0.5g gravity, 50% water.
Knowing those pesky and persistent Terrans, those worlds would have been brought into empire during the Rule of Man. That's not to say there weren't Vilani or Suerrat there already, as we know from other borders (cough, Gashikan, cough) that the Ziru Sirka had poor border control.
I think there's interesting fodder there. Worlds with Vilani contact but not Vilani control, suddenly meeting Solomani oppressors. Maybe old deals and treaties nullified or forgotten. Bitterness about the Empire.
Just within Ilelish, you have two separate revolts and rebellions. Plus the Year 76 Pacification Campaigns.
It was 399 when Ilelish and the other HiPop worlds in the sector started negotiating with the Imperium for their own autonomous region, motivated by wanting control over interstellar trade "for greater profitability." I imagine that the HiPop systems in Verge joined in.
The 418 Ilelish Revolt ended in 435 with the Imperium sterilizing the capital planet's tropical zone from orbit and they forcibly moved the capital to Dlan. Bitterness about the Empire.
Dulinor's revolt wasn't a solo thing. He had backing of all of the Imperial Naval Intelligence organization within Ilelish. He presumably had the fleets in Ilelish and Verge? There had to be a pretty strong anti-Imperial sentiment in the sectors spinward of Core.
I'm saying, let's figure out that reason for all the unrest in Verge and amplify it a bit for the character of the setting. This is a sector that isn't that far from Core but has never really accepted rule.
Can we assume that some of those fringe systems had Solomani nobility who had found their place in Imperial government, but whose loyalties were tested during Dulinor's rule?
Oh, I just noticed that the "Ripples in the Imperium" map on page 14 of Mt Rebellion Sourcebook shows a lot of Rift-edge systems NOT part of the Third Imperium in
1116... That's MAJOR.
(Are we allowed to post book maps here?)
With no minor alien races and no other humans aside from the Suerrat in the sector, and with J2 needed to move around Verge freely in the first place, why is Verge even counted as part of the Ziru Sirka?
I'm guessing a lot of double-J1 jumps between the J2 gaps.
Do you have a timeline for when the Vilani and Solomani achieved J1, J2, J3, etc.?