The word Accra is believed to be derived from the Akan word nkran, meaning "ants", a reference to the numerous anthills seen in the countryside around Accra. The city was first settled in the 15th century, when the Ga people migrated there from their previous settlement at Ayawaso, 10 miles (16 km) north of Accra. The site was advantageous due to its distance from the Ga's main rivals, the Akwamu people. Initially, Accra was not the most prominent trading centre; the trade hubs of the time were the ports at Ada and Prampram, along with the inland centres of Dodowa and Akusa. However, Accra gained status as a centre for the slave trade with the Europeans who had built the nearby outposts of James Fort and Ussher Fort. By the 17th century, the Portuguese, followed by the Swedish, Dutch, French, British and Danish, had constructed forts in the town. Such activity went on in Accra until the abolition of the slave trade in 1807
