This list includes those planets directly on a superhyperroute bordering either end of the Slice.
During the Jedi Civil War which started in 3959 BBY with the surprise attack on Foerost. Revan and Malak launched a massive campaign through the Northern edge of the slice. Assumably to essentially divide the Republic in half and weaken their ability to defend itself.
Prior to the creation of a full map of the galaxy, the Slice was depicted as being much smaller than currently; sources stated that it contained under a thousand settled planets, and less than 1% of the galaxy. While creating the map, Daniel Wallace found that those numbers could not be reconciled with his starting info, and he ultimately had to reject them.