Carib Indians occupied the islands of the West Indies for hundreds of years before the British and French began settlement in 1623. During the 17th century, Saint Kitts became the premier base for British and French expansion into the Caribbean. The French ceded the territory to the UK in 1713. At the turn of the 18th century, Saint Kitts was the richest British Crown Colony per capita in the Caribbean, a result of the sugar trade. Although small in size and separated by only 3 km (2 mi) of water, Saint Kitts and Nevis were viewed and governed as different states until the late-19th century, when the British forcibly unified them along with the island of Anguilla. In 1967, the island territory of Saint Christopher-Nevis-Anguilla became an associated state of the UK with full internal autonomy. The island of Anguilla rebelled and was allowed to secede in 1971. The remaining islands achieved independence in 1983 as Saint Kitts and Nevis. In 1998, a referendum on Nevis to separate from Saint Kitts fell short of the necessary two-thirds majority.