FACTBOX: Key facts about Northern Ireland

(Reuters) - Northern Ireland's main Protestant and Roman Catholic political parties launched a power-sharing government on Tuesday aiming to put a final end to decades of violence.

Following are some facts about Northern Ireland:

POPULATION - 1,685,000.

AREA - 5,500 sq miles on an island shared with the bigger Republic of Ireland to the south and west.

RELIGION - 2001 census showed 53.1 percent of population Protestant and 43.8 percent Roman Catholic.

GOVERNMENT - Part of the United Kingdom. Under the 1998 Good Friday peace agreement a Protestant-Catholic power-sharing assembly was established in Belfast with limited home rule powers. Suspended in 2002 and direct rule from London resumed.

HISTORY - Northern Ireland's sectarian divisions can be traced back to the 17th Century when Protestant settlers from Scotland and England were "planted" in the northeastern part of the island to bolster the authority of the English Crown.

An abortive uprising against British rule in Dublin in 1916 paved the way for 1921's Anglo-Irish Treaty which partitioned the island, separating the mainly Protestant northeast from the overwhelmingly Catholic south and west.

Simmering sectarian tensions exploded into violence in the late 1960s, with British troops under attack from Irish Republican Army guerrillas. Militant Protestant "loyalist" groups sought to defend British rule by killing Catholics.