Britain played a prominent role in the Atlantic slave trade, especially after 1640, when sugar cane was introduced to the region. At first, most were white Britons, or Irish, enslaved as indentured labour – for a fixed period – in the West Indies. These people may have been criminals, political rebels, the poor with no prospects or others who were simply tricked or kidnapped. Slavery was a legal institution in all of the 13 American colonies and Canada (acquired by Britain in 1763). The profits of the slave trade and of West Indian plantations amounted to under 5% of the British economy at the time of the Industrial Revolution.