The history of Ireland begins in prehistoric times. People began farming on Ireland thousands of years ago.
The Celts moved there about 2,500 years ago and divided Ireland into many small kingdoms. In the 5th century, Saint Patrick brought Christianity to Ireland; it is still the dominant religion on the island today. The Vikings and later the Normans invaded in the Middle Ages.
Eventually, Ireland became part of the United Kingdom. After the Irish War of Independence in 1919-1921, most of Ireland became an independent country, the Republic of Ireland. However, Northern Ireland stayed in the United Kingdom, and is still a part of the U.K. today.