Why is the story of ayuba suleiman diallo unusual?

I believe the answer is: few slaves could write down their experiences

The slaves were purchase and forced to work at plantations with no salary and barely enough time to rest.  Because of this, almost all slaves were illiterates (cannot read or write). Because of this, historians found it difficult to find a writing that depict the slaves' experience during that period.

the density would be a smaller number.

muslims have taken his goods and products to different parts of asia an indonesia. sometimes just traveled and trade, but in other occasions, stayed in the place and made a living.

trade was the key for muslims economies to prosper. their commerce routes reached far places like malaysia and java in the 11th century.

another important factor for prosperity was that muslim states served as the middle point for european traders.

they used to travel by land but sailing the seas -the indian ocean- really increase the exportation of products.