Other European traders had joined in gold trading by the mid-17th century, most notably the Swedes, establishing the Swedish Gold Coast (Svenska Guldkusten), and Denmark-Norway, establishing the Danish Gold Coast (Danske Guldkyst ''or'' Dansk Guinea). Portuguese merchants, impressed with the gold resources in the area, named it ''Costa do Ouro'' or ''Gold Coast''. Also beginning in the 17th century – in addition to the gold trade – Portuguese, Dutch, English, and French traders also participated in the Atlantic slave trade in this area.