Former vassal states of the Confederacy of Independent Systems covered a fairly broad range.
During the Clone Wars, the Kingdom of Dawn had gradually grown into Count Dooku's most powerful subordinate force. The Trade Federation and InterGalactic Banking Clan may have possessed greater economic strength, but in terms of military power, no one in the Confederacy of Independent Systems could compare with the Kingdom of Dawn.
Although the Kingdom of Dawn later made a separate peace with the Galactic Empire and unilaterally withdrew from the war, by then the Confederacy of Independent Systems had already fallen apart. Nearly every faction was looking out for its own way forward, so what would once have been regarded as betrayal did not actually provoke much reaction within the Confederacy.
Afterward, the Confederacy of Independent Systems was defeated in the four-year Saleucami planetary battle, and the Super Fortress it had built in a desperate final gamble was completely destroyed. After that, before Darth Vader's fleet could even come knocking, the Confederacy of Independent Systems disintegrated, with its major member planets surrendering at the first sign of trouble.
The conquest of Saleucami Planet had dragged on intermittently for four years, but less than three months passed between that victory and the destruction of the Confederacy of Independent Systems.
This left behind a consequence—the powerful factions within the Confederacy of Independent Systems had not suffered the devastating blows they had in the original storyline. Aside from the InterGalactic Banking Clan, which had already split apart and been nationalized by both warring sides, major corporate giants such as the Trade Federation, Technological Alliance, and Corporate Alliance retained considerable strength and surrendered to the Galactic Empire.
But these powers quickly discovered that the Galactic Empire's exploitation of them was unimaginably brutal. It practically wanted to skin them alive!