Cross River state, Nigeria; their dialect is Efik (in the Benue-Congo branch of Niger-Congo languages) has become the literary language of all educated Efik-Ibibio speakers. The Efik, an offshoot of the Ibibio, migrated down the Cross River during the first half of the 17th century and founded Creek Town, Duke Town, and other settlements. Because of a European error in confusing their territory with that of the Kalabari Ijo (known as New Calabar), the Efik area became known as Old Calabar. Originally a fishing community, Old Calabar developed into a major trading centre from the 17th to the 19th century, exporting slaves and later palm oil in return for European goods. European ships had to pay a duty to Efik chiefs for the privilege of trading. During the 20th century a large part of the Efik population moved from the towns and settled in farming villages in the forest.