WI Incel rebellion happens in the Abbasid Caliphate

What if they were restricted from being able to obtain more slaves by more powerful foes around them?

Since the OP specified the Abbasids, it could be a rival Islamic state in Yemen/Oman on one side and the Byzzies on the other.

if the Abbasids couldn't obtain slaves it would seriously effect the economy and depending on the period its military capability. although without the reliance of slave soldiers the Caliphate might have been more unified and wouldn't have split up.
 
I don't know why the states did not conscript single men as soldiers to deal with the large male population. You pretty much abduct the women of the enemy and kill the overflow men you have in your society. Sounds bad but how else can you deal with this.
 
With any POD, have an incel rebellion emerge in the abbasid caliphate due to chronic shortage of women due to polygamy.

No war by the Abbasids for some decades and promotion of polygamy by the clergy. A lot of young men would not have a chance to get wives and will pretty much be pissed at the government.

Expect a lot homosexuality in the Abbasid realm. The clergy would be divided on the matter.
 
Not quite, but much of the rebel armies, especially in the early stages of the rebellions, were composed of poor, young, wifeless men (called guanggun, "bare branches", in Chinese). Because they lacked family ties and the mainstream of Chinese society did not have much place for secular unmarried men, the guanggun had little choice but to join wandering groups of male vagrants—and because the Chinese state disapproved of these groups, seeing them (perhaps correctly) as little more than bands of marauding rapists, rioters, and would-be rebels, it cracked down harshly on them. This made the guanggun class of frustrated young men perhaps the easiest demographic to mobilize against the state.

Chinese policy makers were apparently unwilling to face the fact that the issue would not fix itself without righting Late Imperial China's ridiculous sex ratio (estimated at about 120 men per 100 women) by banning female infanticide and polygamy and instead spent administrative resources fighting the symptoms (the guanggun bands) as well as it could.

The Manchu conquerors actually took advantage of this - the early-Qing Empire often married Manchu women off to single Han/Ming soldiers. This kind of worked because 1) extremely high Manchu male death rates as Manchu officers were expected to be "first through the breach" in front of any Han soldiers and 2) Manchus, unlike their neighbors to the South, both practiced and heavily encouraged widow remarriage. Though the intense culture shock required IIRC meant that the Qing government had an entire Imperial sub-bureau that was just mixed marriage counselling.

Edit: I recall reading a rather amusing story about soldiers defecting to the Manchu because they were promised land and wives, which the Qing did deliver. Except the land was malarial swampland in Manchuria. And for the wives, they were taken to a local Manchu prison and told to take their pick.
 
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