History of Slavery Around the World
https://discover.hubpages.com/politics/History-of-Slavery-Around-the-World
Contrary to popular belief, the first slaves in the American colonies were not Africans. Also, the majority of Africans taken from their homelands for the purpose of slavery were not destined for the shores of what would eventually evolve into the United States. Slavery was a documented “established institution” dating back to as early as 1760 B.C., where it is referred to in the Code of Hammurabi.
Slavery was an accepted part of society in ancient cultures such as Greece, Assyria, and Egypt, and at one time, the Roman Empire’s total population consisted of 25% slaves, with Italy’s slaves comprising 30% to 40% of its total population. By 500 B.C., slaves comprised upwards of a third of the population in some Greek city-states. In Sparta following several slave revolts about the year 600 B.C., the Spartans restructured their city-state into an authoritarian regime, for the leaders decided that only by turning their society into an armed camp could they hope to maintain control over the numerically dominant enslaved population.
From the pre-Christian era up to colonization of the New World, slavery was an accepted part of daily life in countries and cultures across the globe, and whether or not a particular culture was enslaved was generally determined by their weakness in warfare. To the victors go the spoils, which in this case were the indigent peoples of the conquered lands. Slaves consisted of Irish, Turkish, Chinese, Arab, Persian, Greek, and many other cultures, and was not restricted to one particular race, ethnicity, culture, or country.
The human embarrassment of slavery belongs at the source of slavery which is still actively practiced in Africa, the Near East, and elsewhere.
The real issue here is not the ethics of slavery, but rather the financial incentive to charge against the Untied States "deep pockets" and largess.
Rather than being thankful for the freedoms of current America, some of the population would rather dwell in the negative 'sins of the past' debate.