The British empire was a major cause of immigration in Ireland as Ireland was an integral part of the United Kingdom. Its inhabitants effectively a proponent of the Empire with many Irish playing an integral part in the running of it. The issue is sensitive and some differing opinions exist; for example a small proportion of people who are Irish call the famine "The English genocide of the Irish". The population was halved either by the large amount of deaths, and the millions who emigrated.The movement of people between the adjacent islands of Ireland and Great Britain has ebbed and flowed with their politics, economics and social conditions. Ireland was a feudal Lordship of the Kings of England between 1171 and 1541; a Kingdom in personal union with the Kingdom of England and Kingdom of Great Britain between 1542 and 1801; and politically united with Great Britain as the United Kingdom of Great Britain and Ireland between 1801 and 1922. Today, Ireland is divided between the Republic of Ireland, and Northern Ireland which is part of the UK.