 The Irish Football Association ( IFA ) was originally the governing body for soccer across the island . The game has been played in an organised fashion in Ireland since the 1870s , with <unk> F.C. in Belfast being Ireland 's oldest club . It was most popular , especially in its first decades , around Belfast and in Ulster . However , some clubs based outside Belfast thought that the IFA largely favoured Ulster @-@ based clubs in such matters as selection for the national team . In 1921 , following an incident in which , despite an earlier promise , the IFA moved an Irish Cup semi @-@ final replay from Dublin to Belfast , Dublin @-@ based clubs broke away to form the Football Association of the Irish Free State . Today the southern association is known as the Football Association of Ireland ( FAI ) . Despite being initially <unk> by the Home Nations ' associations , the FAI was recognised by FIFA in 1923 and organised its first international fixture in 1926 ( against Italy ) . However , both the IFA and FAI continued to select their teams from the whole of Ireland , with some players earning international caps for matches with both teams . Both also referred to their respective teams as Ireland . 
