Why are there so many black people in America besides Africa and Oceania?

The slave trade began in the 15th century. European colonists sold African blacks to America as slaves, and a large number of African blacks came to America in this way.

Slave traders set out from Europe and arrived in Africa by boat. After capturing blacks in various despicable ways in Africa, they transported slaves to America, sold them to American planters, and then shipped American gold and industrial raw materials back to Europe. This is known as the "triangle trade". The Portuguese were the first to trade slaves, but the British came from behind and became the main operator of the "triangle trade".