There's not that much written about this these days, but here's a brief sample from an essay on the Tuareg blacksmith/artisan caste of the Sahara:
What is most striking about many Inedan is their Negroid appearance, or rather, their completely distinct physiognomy, in which Negroid traces are often very clear. A Touareg can identify an artisan merely from his facial features, even if he comes from a region thousands of miles away across the desert. This has lead to speculation that the Inedan are descended from an ancient black race who lived in the desert before the Berber tribes of the north came south and who were subsequently subdued and forced to work for their new ‘whiter’ overlords.And this pattern is seen much farther from sub-Saharan Africa, such as in Jordan.
In contrast, in Europe, "Smith" is often the modal surname, suggesting that being a blacksmith was one of the more common occupations outside of farming and that smiths tended to have reasonable Darwinian success. And that sounds reasonable: being a blacksmith isn't a great job — it's hot, it requires much strength.
But, as a rudimentary technologist, it's not the worst job either. A few Western blacksmiths, such as John Deere, turned into inventors or tycoons.
So it's not immediately evident why the dominant Caucasians of the Middle East often reserved blacksmithing for a black caste. Anybody know why? This is an obscure question, but trying to understand things that seem puzzling can often lead to a better overall understanding of the way of the world.
Perhaps we can learn something about the differing fates of the West and the Muslim world from their differing attitudes toward blacksmiths. The American writer Henry Wadsworth Longfellow's once famous poem The Village Blacksmith begins:
UNDER a spreading chestnut tree The village smithy stands; The smith, a mighty man is he, With large and sinewy hands; And the muscles of his brawny arms Are strong as iron bands.
His hair is crisp, and black, and long, His face is like the tan; His brow is wet with honest sweat, He earns whate'er he can, And looks the whole world in the face,