ギリシア祖語
Following the initial split, the language tree shows the formation of separate Tocharian, Greek, and then Armenian lineages, all before 6000 BP, with all of the remaining language families formed by 4000 BP. We note that the received linguistic orthodoxy (Indo-European is only 6000 years old) does approximately fit the divergence dates we obtained for most of the branches of the tree. Only the basal branches leading to Hittite, Tocharian, Greek and Armenian are well beyond this age."
↑ Hamp, Eric P. (1960). “Notes on Early Greek Phonology”. Glotta 38 (3/4): 187-203. https://www.jstor.org/stable/40265810.