Why are there so many blacks in European countries?

First, the black slaves brought from Africa during the triangle trade period gave birth to children there, which made many black people in European countries;

Second, comprehensive factors such as immigration.

Triangle trade mainly refers to17-19th century (after the opening of the new air route) when European and American businessmen transport cheap industrial products (guns, etc.). ) go to Africa to exchange slaves, transport slaves to America for sale, buy back production materials (gold and silver, industrial raw materials) from America, make goods and then go to Africa to exchange slaves. Because its trade involves Europe, America and Africa, it is called. In the past, Europe, America and Asia carried out large-scale triangle trade; Atlantic triangle trade refers to the trade between Europe, West Africa and America.