The first signs of habitation appeared around 7000 BC, but the remains of tombs and stones date back to 3000 BC. The island was then occupied by the tribals who were there until the Celts conquered it in 300 BC. The Celts were converted to Christianity in the 5th century by St Patrick, the patron saint. The Vikings also arrived in the 8th century, and it continued till 1014 until the natives expelled them. After the Vikings had come, the Normans who got the country in England and a lot of migrants arrived from England by 1800. The failure of the potato crop in the 19th century was a major drawback for the country. In 1921, the Republic of Ireland was created after getting separated from the British, and it composed of 26 counties on the island. It joint EEC in 1972 and EU in 1999.