Researching the early Islamic period in North Africa is challenging for many reasons
-The written sources usually used for this period, like histories, pay less attention to the Islamic lands west of Egypt. How often does al-Ṭabarī refer to Ifrīqiya, for example? And...

-There are fewer non-Muslim eye-witness accounts than for regions like Egypt or Syria.
-There are local histories but almost all were written at least 3 centuries later. The authors worked from earlier material, but it’s impossible to say what was changed in the process. And..

-There’s very little material documentation. The papyrus corpus in Egypt helps us understand the administration of the early Islamic state there, but there’s nothing like that for Ifrīqiya. And..

- Colonial archaeology in the region was focused on the classical and not the Islamic period. Some archaeologists destroyed the Islamic levels completely to get to the Byzantine and Roman levels below them.

I can’t explain the causes of these limitations in a tweet. But moving from 14th century Syria to 8th century Ifrīqiya has been like slipping from the sea into a swimming pool, source-wise.

It’s even more difficult to find sources on the slave trade. Lots of works refer to slaves and slave purchase, either in passing or, like Ibn Buṭlān, in more detail. But there’s little detailed description of how the trade functioned, the routes it used, who acted as middlemen…

Material evidence for slave trade is virtually indistinguishable from other forms of human transport. No shackles for archaeologists to dig up and use to map the trading sites.

There are Islamic coins in far-flung regions, but we should be careful before assuming these were payment for slaves. Identifying how slaves were transported across to Africa to the Islamic Empire is largely a matter of finding trade routes for other goods...

and then seeing if the sources suggest that slaves were also transported along these paths.

So it's tricky. I'll tweet more about what sources I find useful shortly.