The ancient Greeks did not collect/trap people to sell as part of a slave trade in the way the British developed over many, many centuries, and more recently.
The Greeks used their captured prisoners from war as slaves. Practicalities may have meant some of them were swapped or sold but there was never a trade in the merchant sense of rounding-up innocent people to sell.
How did Aristotle develop a concept of a "master race" ? You are completely off-track - and perhaps are one of those he identified as requiring more instruction.