This is our World organized by languages spoken, ending up with the old colonial empires.
According to the Economist‘s article:
A unified Arabia would stretch from the Atlantic to the Indian Ocean. There might be the odd squabble between Sunnis, Shias, Christians and adherents of archaic notions of nation; but united by a common tongue, the Arabs would be sure to get along fine, especially if they teamed up to smite the Persian-speakers on the other side of the Gulf. The two Koreas would become one, which might be a good thing—or not, depending on which system prevailed.