 As created in 1999, the region covered the whole of the preserved county of Dyfed, most of the preserved county of Powys and parts of the preserved counties of Clwyd and Gwynedd.Other parts of Powys, Clwyd and Gwynedd were within the North Wales electoral region.However, boundaries changed for the 2007 Welsh Assembly election and the region now covers all of the preserved county of Dyfed, all of the preserved county of Powys and part of the preserved county of Gwynedd.