Slavery appeared and spread in societies that have fallen to the agricultural production. On the one hand, this production, particularly with primitive technique requires very significant labor costs, on the other hand, the worker can produce significantly more than is necessary to sustain life. The use of slave labor was economically justified and, of course, widespread. Then there was the slave system, which lasted for many centuries – at least since ancient times to the 18th century, and in some places even longer.
Slavery, almost everywhere in Europe replaced serfdom; it was restored in a new light in the 17th century, after the beginning of the era of great geographical discoveries. On the territories colonized by Europeans a large scale agricultural production began, which required a large number of workers. The conditions of life and production in the colonies were very close to those that existed in ancient times: large expanses of uncultivated land, low population density, the possibility of extensive farming methods, with the most simple tools and basic technologies. In many places, especially in America, it was almost impossible to find workers: the local population had no desire to work for the newcomers and free settlers were not going to work on the plantations. At the same time during the development of Africa by white Europeans it was found easy enough to get a virtually unlimited number of employees, grabbing and turning indigenous Africans into slavery. African nations were mostly at the stage of the tribal system and the initial stages of state-building, their technological level made it impossible to resist the Europeans, who had equipment and firearms. On the other hand, they were familiar with slavery before the arrival of Europeans and slaves considered as one of the products for profitable trade.
In Europe, slave labor renewed and a massive slave trade began, which flourished until the 19th century. Africans were captured in their native lands (usually by Africans themselves), loaded on ships and sent to the destination. Some of the slaves went to the metropolis, but the majority was sent to the colonies, mostly in America. There they were used for farm work, mostly on plantations. At the same time in Europe, criminals sentenced to hard labor in the colony were sent and sold into slavery. Irish were dominated among the white slaves that were captured by the British captured during the conquest of Ireland.
In total, around 13 million African slaves were imported to the United States. On average, from 3-5 captured slaves only one was delivered on the plantation, the others died during capture and transportation.
Slavery appeared and spread in societies that have fallen to the agricultural production. On the one hand, this production, particularly with primitive technique requires very significant labor costs, on the other hand, the worker can produce significantly more than is necessary to sustain life. The use of slave labor was economically justified and, of course, widespread.