Northern Ireland national football team
In 1920, Ireland was partitioned into Northern Ireland and Southern Ireland. In 1922, Southern Ireland gained independence as the Irish Free State, later to become a republic under the name of Ireland. Amid these political upheavals, a rival football association, the Football Association of Ireland, emerged in Dublin in 1921 and organised a separate league and international team. In 1923, at a time when the home nations had withdrawn from FIFA, the FAI was recognised by FIFA as the governing body of the Irish Free State on the condition that it changed its name to the Football Association of the Irish Free State. The Irish FA continued to organise its national team on an all-Ireland basis.
Irish border question
In 1922, the Irish Free State repatriated its national legislature from London, setting the stage for full national independence, while Northern Ireland remained under the governance of the United Kingdom. Consequently the dividing line between these two parts of the island became an international border. Trade in goods and services across this frontier became subject to differing tax and tariff arrangements and an infrastructure of Customs posts was put in place at designated crossing areas. All traffic was subject to inspection by the jurisdiction it was entering. This could entail full vehicle searches with consequent delay and inconvenience. However, passport checks were not applied because the Republic of Ireland and Northern Ireland were part of the Common Travel Area.