Since Ireland was granted total independence in 1949 Northern Ireland has been struck by violence that arose from conflict over what issue?

Since gaining independence in 1949, Northern Ireland has experienced significant violence primarily due to the conflict between nationalist/republican communities, who primarily identify as Irish and seek unification with the Republic of Ireland, and unionist/loyalist communities, who identify as British and wish to remain part of the United Kingdom. This sectarian divide has led to decades of conflict known as "The Troubles," marked by paramilitary violence, civil unrest, and political strife, deeply rooted in historical, cultural, and economic disparities.