The Inner Baronies were the baronies closest to human civilization during the time of Arthur Eld to Roland's youth until they were largely driven into chaos like the rest of All-World. The Inner Baronies were ruled by the Gunslinger warrior elite from their seat at the city of Gilead located in the Barony of New Canaan.
New Canaan is most certainly a part of Inner Baronies but it is a little iffy on what other Baronies are in this geographical location. The Barony of Mejis, where Roland and his Ka-tet of youth travel to is close to New Canaan but it is said to be in 'Out-World', although they do appear to have a close connection with the Gunslingers. Cressia, which was sacked and over taken by John Farson's forces is said to be part of the Affiliation and thus is part of the Inner -Baronies. Territories in All-World such as Garlan and Delain , which are not under the direct administartion of the Affiliation cannot be considered part of the Inner-Baronies but are in their own part of the world. In fact these two regions have been referred to as Kingdoms quite often (especially Delain) and thus we recognize them as being quite different.