section_path: History/Height of the slave trade
section_name: Height of the slave trade
paragraph_text: Height of the slave trade
  
  Slavery had long been practiced in Africa. Between the 15th and the 19th centuries, the Atlantic slave trade took an estimated 7–12 million slaves to the New World. In addition, more than 1 million Europeans were captured by Barbary pirates and sold as slaves in North Africa between the 16th and 19th centuries.
  
  In West Africa, the decline of the Atlantic slave trade in the 1820s caused dramatic economic shifts in local polities. The gradual decline of slave-trading, prompted by a lack of demand for slaves in the New World, increasing anti-slavery legislation in Europe and America, and the British Royal Navy's increasing presence off the West African coast, obliged African states to adopt new economies. Between 1808 and 1860, the British West Africa Squadron seized approximately 1,600 slave ships and freed 150,000 Africans who were aboard.
  
  Action was also taken against African leaders who refused to agree to British treaties to outlaw the trade, for example against "the usurping King of Lagos ", deposed in 1851. Anti-slavery treaties were signed with over 50 African rulers. The largest powers of West Africa (the Asante Confederacy, the Kingdom of Dahomey, and the Oyo Empire) adopted different ways of adapting to the shift. Asante and Dahomey concentrated on the development of "legitimate commerce" in the form of palm oil, cocoa, timber and gold, forming the bedrock of West Africa's modern export trade. The Oyo Empire, unable to adapt, collapsed into civil wars.