A peer-reviewed publication
UNIVERSITY OF BASEL
Extreme dry conditions contributed to the decline of the ancient South Arabian kingdom of Himyar. Researchers from the University of Basel reported these findings in the journal Science. Combined with political instability and war, the drought has left a region in turmoil, thereby creating conditions on the Arabian peninsula capable of spreading the nascent religion of Islam. .
In the highlands of Yemen, traces of the Himyarite Kingdom can still be found today: terraces and dams form part of a particularly complex irrigation system that transforms the semi-desert into fields. fertile. Himyar has been an established part of South Arabia for several centuries.
However, despite its former strength, in the sixth century C.E., the kingdom entered a period of crisis, culminating in the conquest of the neighboring kingdom of Aksum (now Ethiopia). A previously overlooked factor, namely extreme drought, may have been a contributing factor in the upheavals in ancient Arabia from which Islam emerged in the seventh century. These findings were recently reported by researchers led by Professor Dominik Fleitmann in the journal Nature. Science.
Petrified water serves as climate record
Fleitmann’s team analyzed layers of stalactites from the Al Hoota Caves in present-day Oman. The rate at which stalactites grow and the chemical composition of its layers (see box) are directly related to the amount of precipitation that falls above the cave. As a result, the shape and isotopic composition of the stalactite deposits present a valuable historical climate profile.
“Even with the naked eye, you can see from the stalactite that there was a very dry period that lasted several decades,” says Fleitmann. When the amount of water dripping down the stalactite will be less, the amount of water flowing down the sides will be less. The rock grows to a smaller diameter over the years with a higher drip rate.
Isotope analysis of the stalagmite layers allowed the researchers to draw conclusions about annual precipitation. For example, they not only found that there was less rainfall over a longer period, but also that there must have been an extreme drought. Based on the radioactive decay of uranium, the researchers were able to date this dry period as early as the sixth century AD, though only with an accuracy of 30 years.
Detective work in case of Himyar’s death
Fleitmann explains: “Is there a direct temporal correlation between this drought and the decline of the Himyarite Kingdom, or whether it really didn’t begin until much later – that cannot be determined with certainty. As a result, he further analyzed climate reconstructions from the region and explored historical sources, collaborating with historians to narrow down the duration of an extreme drought lasting several years.
“It’s a bit like a murder case: we have a deadly kingdom and we’re looking for the culprit. Step by step, the evidence has brought us closer to the answer,” said the researcher. Helpful sources include, for example, Dead Sea water level data and historical documents that describe a drought that lasted several years in the area and dated to 520 AD, actually connecting between extreme drought with crisis in Himyarite Kingdom.
“Water is absolutely the most important resource. It is clear that a decrease in rainfall and especially several years of extreme drought can destabilize a vulnerable semi-desert kingdom,” says Fleitmann. Furthermore, irrigation systems require constant maintenance and repair, which can only be achieved with tens of thousands of well-organized workers. Himyar’s population, affected by water scarcity, probably could no longer afford this costly maintenance, exacerbating the situation.
Political instability in its own territory and a war between its northern neighbors, the Byzantine and Sasanian Empires, swept into Himyar, further weakening the kingdom. When its western neighbor Aksum finally invaded Himyar and conquered the kingdom, the formerly powerful state completely lost its meaning.
Historical turning point
“When we think of extreme weather events, we usually think of only a short period of time afterward, limited to a few years,” says Fleitmann. The fact that climate change can lead to countries being destabilized, thus changing the course of history, is often overlooked. “The people had to go through great hardships due to famine and war. This means that Islam has encountered fertile ground: people are looking for new hope that can bring people together as a society. The new religion has suggested this”.
That doesn’t mean the drought directly led to the emergence of Islam, the researcher stressed. “However, it was an important factor in the upheaval in the Arab world in the sixth century.”
Box: Precipitation and stalagmite
In tropical and subtropical regions, there is a relationship (correlation) between precipitation and its isotope composition, also known as the “quantity effect”. The more it rains, the lower the ratio between the lighter and heavier oxygen isotopes, 16O and 18O, change in favor of the lighter 16O in the precipitate. These changes are recorded in stalactites in Oman, as it is formed from dripping rainwater. Based on isotope measurements of the limestone layers of stalactites, it is possible to accurately determine the ratio 16O and 18O and, in conjunction with uranium dating, to reconstruct its precipitation at any time.
10.1126 / science.abg4044
Drought and social change: the environmental context for the emergence of Islam in late Antique Arabia
ARTICLE PUBLICATION DATE
June 17, 2022