The correct answer is - plate tectonics.
The convection currents in the mantle, are having very high temperatures and very high pressures. Because of that, they managed to crack the crust, and thus divide the surface of the Earth in multiple peaces, or as we call them, tectonic plates. The very high pressure from bellow manages to push the tectonic plates in certain direction, and even though that movement is only a couple of cm per year, on the long term it has huge effects on everything on the planet.
The spread began in the 7th to 9th century, originally brought to North Africa under the Umayyad Dynasty. Trade networks were extensive, spanning through north and west Africa which created a medium in which islam peacefully spread through the merchant class.
Answer: "oasis" .
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