What led to Spread of Islam?

Harassment of Religiously Unaffiliated People Rose in Eight Years

In a recent study, researchers from the University of Basel said that extreme drought conditions in Arabian peninsula made possible the spread of Islam at that time.

Moreover, the researchers noted that the extreme conditions contributed to the decline of the ancient South Arabian kingdom of Himyar, which paved the easy for the emergence of the new religion.


On the plateaus of Yemen, traces of the Himyarite Kingdom can still be found today: terraced fields and dams formed part of a particularly sophisticated irrigation system, transforming the semi-desert into fertile fields. Himyar was an established part of South Arabia for several centuries.

However, despite its former strength, during the sixth century CE the kingdom entered into a period of crisis, which culminated in its conquest by the neighbouring kingdom of Aksum (now Ethiopia). A previously overlooked factor, namely extreme drought, may have been decisive in contributing to the upheavals in ancient Arabia from which Islam emerged during the seventh century. These findings were recently reported by researchers led by Professor Dominik Fleitmann in the journal Science.


Fleitmann and the team of researchers analyzed the layers of a stalagmite from the Al Hoota Cave in present-day Oman. The stalagmite’s growth rate and the chemical composition of its layers are directly related to how much precipitation falls above the cave. As a result, the shape and isotopic composition of the deposited layers of a stalagmite represent a valuable record of historical climate.

“Even with the naked eye you can see from the stalagmite that there must have been a very dry period lasting several decades,” says Fleitmann. When less water drips onto the stalagmite, less of it runs down the sides. The stone grows with a smaller diameter than in years with a higher drip rate.

Isotopic analysis of the stalagmites layers allows-researchers to draw conclusions about annual rainfall amounts. For example, they discovered not only that less rain fell over a longer period, but that there must have been an extreme drought. Based on the radioactive decay of uranium, the researchers were able to date this dry period to the early sixth century CE, albeit only with an accuracy of 30 years.


“Whether there was a direct temporal correlation between this drought and the decline of the Himyarite Kingdom, or whether it actually didn’t begin until afterwards that was not possible to determine conclusively from this data alone,” explains Fleitmann. He therefore analyzed further climate reconstructions from the region and combed through historical sources, collaborating with historians to narrow down the time of the extreme drought, which lasted several years. “It was a bit like a murder case: we have a dead kingdom and are looking for the culprit. Step by step, the evidence brought us closer to the answer,” says the researcher. Helpful sources included, for example, data about the water level of the Dead Sea and historical documents describing a drought of several years in the region and dating to 520 CE, which do indeed connect the extreme drought with the crisis in the Himyarite Kingdom.

It is clear that a decrease in rainfall and especially several years of extreme drought could destabilize a vulnerable semi-desert kingdom, said Fietmann. Furthermore the irrigation system required constant maintenance and repair, which could only be achieved with tens of thousands of well organised workers. The population of Himvar, stricken by water scarcity, was presumably no longer able to ensure this laborious maintenance, aggravating the situation further.

A war between its northern neighbours, the Byzantine and Sasanian Empires, spilling over into Himya, further weakened the kingdom, When its western neighbour of Aksum finally invaded Himyar and conquered the realm, the formerly powerful state definitively lost significance.


The author says that changes in climate could lead to states being destabilised, thereby changing the course of history, is often disregarded. The population was experiencing great hardship as a result of starvation and war. This meant Islam met with fertile ground: people were searching for new hope, something that could bring people together again. The new religion offered this.” That does not mean to say the drought directly brought about the emergence of Islam, emphasizes the researcher. “However, it was an important factor in the context of the upheavals in the Arabian world of the sixth century,” the researcher said.


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