No worries - really happy to help! For a detailed breakdown of military organisation in the 12th century Levant, check out The Crusader Armies by Steve Tibble. For some more detail on Il-Ghazi, the classic reference is a biographical article by Carole Hillenbrand (whose work on the Islamic perspective on the crusades is essential reading imo).

Lots of general remarks in this comment section about jihad and fractiousness and “Arab armies,” but it’s helpful to talk about this specific situation. After the Field of Blood, Il-Ghazi didn’t besiege Antioch, but he did lead a raiding army all the way to the Mediterranean coast.

As far as we can tell from the sources, Il-Ghazi’s army in 1119 was made up primarily of Turkmen nomads. These nomads all owned horses and were capable horseback archers, making them very effective warriors in the right situations. However, their main source of income was actually herding sheep and other herd animals - most of them weren’t professional soldiers. Il-Ghazi recruited these nomads mainly from eastern Anatolia, where they would graze their herds and move from pasture to pasture. The longer they were at war and away from their herds, the less they were able to access their stable source of income.

In order to keep his army in the field for as long as possible, Il-Ghazi had to make sure he could pay them. He couldn’t give them wages like one would to professional soldiers, and he couldn’t give them land in exchange for military service like Frankish lords did to their knights. He basically promised them that they would get paid out of the things they were able to steal from raiding the countryside around Antioch.

The good thing about this system is it let Il-Ghazi and people like him do a lot of raiding, because it paid for itself to an extent. The bad thing about this system is that it restricted the things Il-Ghazi could do other than raiding. A long siege was not an attractive prospect for Turkmen nomads - their risk of injury or death was high, and they weren’t able to get wealth from raiding while besieging a city.

Il-Ghazi didn’t have enough money on hand to keep his army together long enough to besiege Antioch - the only thing he could really do (apart from taking a few small castles) was carry out a massive raiding operation, which is what he did. He didn’t achieve any major strategic victory, but he got lots of money in a short amount of time, and he bolstered his reputation with a group of effective Turkmen fighters.

Il-Ghazi couldn’t keep his army together if he wasn’t consistently raiding the countryside around Antioch to pay them. This was why it was so difficult to keep an army together for extended campaigns.