Complex sentence: Irish was the predominant language of the Irish people for most of their recorded history, and they brought it with them to other regions, notably Scotland and the Isle of Man, where Middle Irish gave rise to Scottish Gaelic and Manx respectively.
Split into simpler sentences: Irish was the predominant language of the Irish people for most of their recorded history. They brought it with them to other regions, notably Scotland and the Isle of Man, where Middle Irish gave rise to Scottish Gaelic and Manx respectively.