The early Parish of Fortingall boundaries were established following the Reformation in the 1500's. It includes Glenlyon to the south, as both were part of Atholl. Following the establishment of the Campbells of Breadalbane in 1680, the area of Glenlyon was considered part of Breadalbane, while Rannoch continued to be part of Atholl. The later boundaries were established following 1889-92.
The parish boundaries of 1840 (red) incorporated portions of the parish of 1930 (black) in Logierait parish.
The regions of Rannoch: