Fuel for what, exactly?

Cooking, and depending on the weather, also for heating.

Dried dung is a common fuel where herding is common and firewood is scarce, and is used today in parts of India, China, Egypt, and other countries in Africa, and is widespread in Iran, the Stans (including Pakistan and Afghanistan), Nepal, Tibet, and Mongolia. It was used as a fuel in Europe into modern times.

The dung is sometimes used as-collected, and sometimes it is processed before use. Processing can include being formed into uniform cakes for consistent burning and quick drying:

• https://commons.wikimedia.org/wiki/File:Brittanydung.jpg

• https://commons.wikimedia.org/wiki/File:Tibet-5874_-Something_smells_here!%282212605065%29.jpg

• https://commons.wikimedia.org/wiki/File:Defense.gov_photo_essay_120707-A-8536E-694.jpg

All three of these examples show dung cakes stuck onto walls for drying. In Mongolia, dung is sometimes used as a building material. Dung is formed into blocks and used to build walls for animal shelters for winter:

• https://survivalpolitics.files.wordpress.com/2015/02/picture6.jpg - from https://survivalpolitics.org/case-study/mongolia/photo-essay-life-and-death-in-inner-mongolia/

In spring, the dung wall is used for fuel.