I recently finished a dissertation chapter on the trade in Slavic captives via al-Andalus into the Islamic world in the 10thC. It was hard to write because I wanted to avoid making any implications that could be weaponized by Islamophobes or slavery apologists... & here we are
https://twitter.com/MirandaKaufmann/status/1334954323349024768

I haven't read this book yet but based on the author bio & the fact that his works include “The Suffragette Bombers” and “British Concentration Camps” I feel safe guessing he’s not a medieval history or Islam specialist & is relying on translations for the Arabic & Latin sources.
Yes, Slavic people (Saqaliba) were trafficked into the Islamic world in the Middle Ages, as were Africans. Many were boys who were castrated and made to serve in palaces as eunuchs.
Arabic sources referred to them as “white” and “black” so there was a racialized element to it, though not equivalent to the transatlantic slave trade.
In my own work I argue that rulers used these slaves as status symbols to convey imperial reach. As with exotic furs, textiles, scents, etc., having lots of slaves who were visibly taken from distant lands would have communicated the geographic extent of one’s power & influence.
These people were not being used for farming, construction, or (as previously thought) filling the military ranks.
There are similarities & differences between this trade & the transatlantic slave trade, just as with all slave trade networks and systems that have existed across history around the world. The history of slavery should not be reduced to a competition over who suffered the most.
The scale of the transatlantic trade was much greater & its effects reverberate in our present society in the form of intergenerational trauma, economic inequality, the prison & police systems, racial disenfranchisement, plantation weddings, etc...
The Saqaliba slave trade is “forgotten” only in that its legacy does not personally affect people on a daily and intimate basis. Its legacy is coin hoards, written sources, and probably some people’s distant DNA.
Historians have been writing about it for generations. See Lévi-Provençal in the 30s–40s & Maurice Lombard in the 70s. I encourage people to read the recent works of Marek Jankowiak, Mohamed Meouak, Michael McCormick, & Alice Rio. Even Bernard Lewis wrote about it.