Complex sentence: Anti-Irish racism includes persecution, discrimination, hatred or fear of the Irish as an ethnic or national group, whether directed against Ireland in general or against Irish immigrants (both protestant and catholic) and their descendants in the diaspora particularly in the early days.
Split into simpler sentences: Anti-Irish racism includes persecution, discrimination, hatred or fear of the Irish as an ethnic or national group. It may be directed against Ireland in general, those who identify as Irish, or Irish immigrants and their descendants in the diaspora, especially in the early days.