Back in the days of the Pharaohs, there were large numbers of people living and working in Egypt. Assuming they used fire to cook their food, as well as for more industrial purposes, they needed a ready source of burnable carbon.
Having been to Egypt I can tell you that there aren’t a lot of forests around these days, although wood could have been plentiful at the time of the Pharaohs.
If you were wealthy you could send out servants to gather wood for burning, but how did the average person get fuel for their personal use? Was coal or oil abundant enough to use as a ready source of carbon?
I believe coal and oil weren’t extensively used until a lot later. Dung fires would have been commonly used, you can make a merry blaze from dried camel turds. I think bundled reeds were used to make torches.
I had assumed they would be using dung to fertilize their fields in order to grow food for themselves and their livestock, but dried dung could certainly be used as a fuel source if there was a dearth of wood… and I assume dung would have been fairly plentiful.
The livestock dung excreted during grazing on the stubble of recently harvested fields helped fertilize them.
Dried cow dung is still a major fuel source in many developing countries. Many’s the stone or concrete wall I’ve seen in India that was completely covered with round cow patties drying in the sun prior to being used to stoke the cooking fire.
In Egypt, the annual Nile flood did a nice job of re-fertilizing the fields.
In other places where rivers didn’t provide such services, utilization of animal dung for fuel did tend to diminish soil fertility over time (along with other factors).