I am thinking here of two groups who work overtime to distinguish themselves from one another precisely because there is so little separating them. Above all, they assert that their ‘languages’ are distinct, whether Danish or Norwegian, Serbian or Croatian. The catch of course is that there is more variation across the dialects within those countries than between them. So Danes and speak with Norwegians, Serbs with Croats and vice versa. Languages? Only in political terms. Compare the fact that some of the ‘dialects’ in China are as distinct as, say, English is from French.
Anyway, who makes up the ancient version? Philistines and Israelites of course. Or is that Phoenicians and Canaanites, Sea Peoples and Hill Peoples? Their ‘languages’ were hardly that at all, for they could understand each other when they spoke their own dialects.