Slavery in the past had nothing to do with lives, slaves had the opportunity of buying their liberty and get paid for it that they could do it after a particular number of years. In Africa, early slavery resulted from warring groups taking captives. Those that were captured were of little of no use, so they were sold and sent to far places because they misbehaved when they were kept close to their homes. Warfare wasn't the only reason for the beginning of slavery, but in some African countries, slavery produced wealth available for the common people. In African countries then, the right of owning lands was insignificant until the colonial official started to impose European law in the 19th century. Land was owned by villages or a group of close-knit and interrelated families and was assigned to families proportionally. So the amount of land a family would need was measured by the numbers of laborers that the family could organize to work on the land. To increase the share of land for the family, they had to invest more in laborers. The easiest and fastest way to invest in laborers was to invest in slaves so many early African societies organized slave raids on far villages.
Between the year 1500 and 1860, at least 12 million Africans were forcibly sent to the Americas. The main countries Africans were taken from were the West African countries: Nigeria, Ghana, Senegal/Gambia also known as Senegambia, Guinea-Bissau, Sierra Leone and the non-West African country, Angola. 24 % of the slaves were taken from Nigeria, 16% of the slaves were taken from Ghana, 24% were also taken from Angola, 13% were also taken from Senegambia, 11% were taken from Guinea-Bissau, 6% were taken from Sierra Leone and 6% were taken from other countries. Less than half a million were sent to North America, but most of the slaves were sent to South America and the Caribbean. .
Slaves were brought to America on the Triangular trade, in which ships went to three trading routes, Africa, America and Europe.