Did a dry weather cycle enable the Islamic empire to supplant the Byzantines? Juan Cole weighs in

Juan Cole of Informed Comment makes some judicious observations about a story we excerpted recently. Well worth reading: Robert Roy Britt of Live Science reports on the research of a team led by University of Wisconsin-Madison professor John Valley that shows increased dryness in the Eastern Mediterranean between 100 and 700 of the Common Era (CE), with dramatic dips in rainfall in 100 CE and 400 CE. It raises questions about whether climate is somehow implicated in the decline of the Roman Empire (traditionally considered to have fallen in 476 CE) and the weakening of the Byzantine Empire in the 600s-700s CE.

Britt does not mention that the 600s were the era in which the Orthodox Caliphs of Islam took greater Syria and Egypt away from Byzantium; these lands were later ruled by the Umayyad Empire. Indeed, within the first century after Islam was founded, its adherents spread out with lightning speed to take over the southern third of the old Roman Empire, as well as the entirety of the Sasanid Empire of Iran. The Muslim conquests after 632 CE are rivaled in history for their speed and extent only by the 13th-century Mongol expansion. The Muslim empire, however, retained its civilizational identity and it was adopted by the conquered, whereas the Mongols were absorbed.

Since the Arab Muslims were from desiccated Western Arabia, they may have been better at dealing with a dry climate; Muslim water-management techniques were superior to those of other civilizations in that era. They may also have had advantages in logistics and fighting technique. .

….Institutions and social arrangements--how people deal with climate change-- are more important than the change itself. Note that pastoral nomads, who take their herds to pasturage wherever it pops up, have advantages over farming peasants in dry eras. Peasants and urban people defect to tribes, or engage in migrations to regain access to water. Since the Bedouin were such an important social element in early Islam, a shift in social and economic power toward pastoralists would have benefited the new religion.

…Climate history enjoyed a vogue a hundred years ago in areas like Roman history, but became discredited because its practitioners tried to explain too much by it and discounted other important explanations. We should avoid these temptations as new climate information allows another run at weather explanations in history.

Manuscript of the collected Theological Works of John VI Kantakouzenos (Constantinople 1370s), today at the Bibliothèque Nationale de France, Paris (Ms. grec 1242)