According to Landnámabók, the settlement of Iceland began in AD 874 when the chieftain Ingólfr Arnarson became the first permanent Norse settler on the island.Others had visited the island earlier and stayed over winter. Over the following centuries, Norsemen settled Iceland, bringing with them thralls of Gaelic origin. From 1262 to 1918, Iceland was part of the Norwegian and later the Danish monarchies. The country became independent in 1918 and a republic was declared in 1944. Until the 20th century, the Icelandic population relied largely on fishing and agriculture, and the country was one of the poorest and least developed in the world. Industrialisation of the fisheries and aid from the Marshall Plan brought prosperity in the years after World War II, and by the 1990s, Iceland became one of the wealthiest and most developed nations in the world. In 1994, Iceland became party to the European Economic Area, which made it possible for the economy to diversify into economic and financial services.