> the barbarians immediately adopted the culture, religion, and especially the (highly written) language of the Romans. This is not really true. It was Clovis

> the barbarians immediately adopted the culture, religion, and especially the (highly written) language of the Romans. This is not really true. It was Clovis and the Franks who made Europe Catholic. Many of the other Germanic tribes were Arian, including the Lombards who essentially destroyed (East) Roman hopes of retaking Italy. Christianity spread by missionaries to many places, particularly Ireland (cf. "Saint Patrick"), and became successful because it helped build alliances among competing tribes. The Ostrogoths ruled over a Roman populace which continued its cultural institutions -- they didn't force everyone to become Goths -- but they retained their Arianism until Justinian retook Italy. The article's graph undermines its own thesis: it's clearly visible that South Asia was just as divided as Europe, but in fact stalls after the first millenium, because that low territory fraction represents nearly 800 years of constant war in the region. Europe, unlike India, has a lot of natural borders, which allowed places like England, Venice, Switzerland, the Netherlands and Portugal to avoid conflict and focus on their internal development, and indeed, all of those places punch well above their weight in the historical record (although the Mediterranean islands generally do not). The only natural border in India protects Kerala, who (poetically) were the first to develop the theory of infinite series in the 16th century. The other outstanding examples of this phenomenon are Oman and, of course, Japan.