How did slavery started?

Answer 1

Slavery began with man from the very start. Slaves were taken in raids and wars. ancient Rome bought and sold slaves as well as took slaves in war. Today there are still slaves, so it hasn't gone away.

Answer 2

Slavery started as a means of using people as a trade for items such as Tobacco, Sugar and Cotton, it started when the British captured free African tribes and transported them upon slave ships in numbers of 400+ The slaves were then transported to the West Indies where they were sold to the owners of plantations, the goods (and some slaves) were then transported back to Britain, this triangular trade became known as the "Slave Trade Triangle"

This was the beginning of the most know slavery trade HOWEVER there have been slaves since pre-recorded times and there has even been mention of slavery in The Bible.

Alternative

The practice of slavery predates recorded history so we cannot know exactly how slavery first started. There is some evidence that Libyans may have had slaves as early as 8000 BC. Many ancient civilizations practiced slavery, including debt slavery, prisoners of war, and abandoned children.

Slavery is at its highest point in today's societies with millions of people held in slavery through debt slavery, forced labour, and human trafficking. The number may be as high as 27 million.

As for slavery as in African people which the British sold to American and West Indies plantation owners, these slaves were able bodied people traded by African tribal chiefs for the goods provided by the British. This would be the slave trade triangle mentioned above.