That's easy. Check the population of villages around 1800 and see how many have surnames. Check wills anytime from 1300 - 1669 and see how many persons are refer to as "slaves" or first name and the country they were taken i.e. Maria i Voulgara or Eleni i Armena. etc.
All persons with names ending in -opoulos, -idis, -oglou, -akis, -akos, -ou, etc are falling in this category. NONE of the original Cretan families had a name ending in -akis. That is a fact.
How many "Vlachos", "Roumeliotis" "Englezos", "Tourkos", "Sklavos", "Rossos", "Armenis"
etc do you know?
The list of the "Greek" families is well known from wills found in Venetian Archives.
Nobody believes it but everybody knows it is true.
The Definition "Greek" was "A Greek Orthodox Person, born to Greek Orthodox parents"; Today, a primary school in Greece has more Albania, and east Europe than Greek. That is a fact.