For those redditors who aren't 'in the know', the Zanj rebellion was a massive slave revolt in lower Iraq near Basra between 869 and 883. Pretty much everything we know about it comes from a single source, a monumental history written by Al-Tabari in the early 900s. He seems to have drawn on some sources that were written a bit closer to events, and although his reputation as a historian has endured for over a thousand years now, that nevertheless means that we're limited in what we can say.

That hasn't stopped speculation, however, and if you are familiar with the Zanj rebellion, chances are you've come across information that has been deeply colored by more recent slave history in the US—that this was a revolt of black Africans who had been ruthlessly exploited on plantation-style farms. This is partly true. Zanj definitely does refer to East Africa in some later sources, so it's probable that most of the slaves involved were actually from East Africa. However, we know that at least one slave who joined in the revolt was Byzantine. Given that his name was Qirtâs, I personally suspect he was a Slavic slave purchased from the market in Constantinople, perhaps captured during the Byzantine invasions of Bulgaria in the 850s or traded from further north by Rus ('Viking') merchants. So there's no reason to assume that 'Zanj' had any sort of ethnic or racial meaning.

But the plantation part is probably true. Lower Iraq has some tremendously fertile ground, but given the agricultural techniques of the time, it was brutally oppressive work. Most of the laborers were probably recently acquired slaves, they seem to have been predominantly male, they were well organized for working on large elite estates, and they lived in the shadow of massive wealth. So they were a pretty dangerous group overall, and in the 860s, all the controls that had kept them in check started to crumble. The Abbasid dynasty suddenly faced revolts in Iran, Egypt, and Syria. Khajarites and a few other religious splinter groups began popping up in revolts across Iraq and the Arabian Peninsula. And the Byzantines were driving the Abbasids back out of Asia Minor (Turkey/Anatolia).

At this explosive moment while the Abbasids were distracted by war and crippled by the loss of important provinces for taxation and food production, the charismatic 'Ali ibn Muhammad appeared to lead the slaves around Basra into open revolt. He had previously been a court poet for the Caliph al-Muntasir (861–2), so presumably he possessed great powers of persuasion. He certainly attracted local peasants to his cause, although we can't know whether this was in solidarity against oppression by their landlords or opportunism following early Zanj successes. Later sources say that 'Ali ibn Muhammad also proclaimed himself a prophet, but this is a stereotypical slur and assumes that the Zanj were practicing Muslims. I don't trust this report. Some sources also claim that 'Ali ibn Muhammad met with Hamdan Qarmat, the leader of a militant sect of Islam, but this report might be part of a smear campaign on the Qarmations after their later revolt in 899, rather than having anything to do with the factual history of the Zanj rebellion.

TLDR So the Zanj rebellion focused on mostly local interests and largely remained local in scale, with early Abbasid efforts directed mostly toward containment. There may have been a meeting between the Zanj leader 'Ali ibn Muhammad and Hamdan Qarmat, who led a group that would later rise up against the Abbasids, but there's reasons to doubt this report. The Zanj rebellion meanwhile benefited from other revolts in Egypt, Syria, Iran, and even closer to home with the Kharijites, while Byzantine advances into Anatolia also helped. These anti-Abbasid campaigns similarly benefited from the Zanj revolt. There is no evidence, however, of any formal coordination. And when the Abbasids finally resolved or gave up on these outside fights, the Zanj revolt was promptly put down. Alexandre Popovic, who has conducted the only major study of the Zanj revolt, warns us not to overestimate its impact on the larger currents of Abbasid history, even while acknowledging a death toll of 500,000 to 2,500,000 victims killed over the course of fourteen years.

---

Alexandre Popovic, The Revolt of African Slaves in Iraq in the 3rd/9th Century, trans. Léon King (Princeton: Markus Wiener Publishers, 1999 [originally published in French, 1976]).