Nigeria, Sept. 13 -- Scotland, Wales, and Northern Ireland are considering leaving the United Kingdom and plan to sign a joint declaration on Monday to demand self-determination.

The Telegraph, a British newspaper, reports that leaders of these three countries will meet in Cardiff, Wales' capital, to discuss the possibility of leaving the United Kingdom.

The United Kingdom of Great Britain and Northern Ireland is made up of four countries: England, Scotland, Wales, and Northern Ireland.

London is the capital city and is located in England. These countries have been politically united for over a century. England and Scotland formally united in 1707 to create Great Britain.

Ireland joined the union in 1801. Although most of Ireland beca...