Isolation and civilization

حَتَّىٰٓ إِذَا بَلَغَ بَيْنَ ٱلسَّدَّيْنِ وَجَدَ مِن دُونِهِمَا قَوْمًا لَّا يَكَادُونَ يَفْقَهُونَ قَوْلًا

Until, when he reached [a pass] between two mountains, he found beside them a people who could hardly understand [his] speech.