In 1851 George Finlay writes in his book “History of Greece”:

“The Albanian population of the Greek kingdom amounts to about 200,000 souls, and the entire race in Europe is not believed to number more than one and a quarter million. In continental Greece they occupy the whole of Attica and Megaris, with the exception of the capitals, the greater part of Boeotia, and a portion of Locris. In the islands, they inhabit the southern part of Euboea and about one third of Andros, while the islands of Salamis, Poros, Hydra, and Spetses are exclusively peopled by a purely Albanian population, as well as part of Aegina and the small neighboring island of Angistri.

In the Peloponnese, they form the bulk of the population in Argolis, Corinthia, and Sicyonia, and occupy considerable districts in Arcadia, Laconia, Messenia, and Elis. Throughout this extensive territory, the prevailing language is Albanian, and in many areas Greek is spoken only by men and very imperfectly, if at all, understood by women. The soldiers of Souli and the sailors of Hydra—the bravest warriors and most skillful mariners in the struggle of Greece to regain her independence—were of the purest Albanian stock, unaltered by any mixture of Hellenic blood.””

Reference

The history of Greece : from its conquest by the crusaders to its conquest by the Turks, and of the empire of Trebizond ; 1204-1461. https://archive.org/stream/historyofgreecef00finl/historyofgreecef00finl_djvu.txt