Complex sentence: Errigal is also the most southern, steepest and highest of the mountain chain, called the'Seven Sisters' by locals Muckish, Crocknalaragagh, Aghla Beg, Ardloughnabrackbaddy, Aghla More, Mackoght (also known as'little Errigal') and Errigal.
Split into simpler sentences: Errigal is also the most southern, steepest and highest of the mountain chain, called the "Seven Sisters" by locals. The Seven Sisters includes Muckish, Crocknalaragagh, Aghla Beg, Ardloughnabrackbaddy, Aghla More, Mackoght and Errigal.