The Caliph was able to mobilize, at least only from within Iraq, 120,000 horsemen, not to mention marines and volunteers, versus the Tatarian army of 200,000 fighters which was besieging Baghdad; and there was a great hope to repel the invaders. However, the Caliph was psychologically defeated and missing the spirit of resistance. He also did not bring up his people on Jihaad, nor did he teach them the arts of fighting, otherwise, where were the training camps that would prepare the youth of the (Islamic) Ummah for a day like that of the Tatars? Why did he not pay attention to swimming, archery and horsemanship? Where was the spiritual preparation of the Ummah to be able to run the life of hard work and struggle?

Of course, I am not prejudiced against the Caliph. The Caliph ruled his state for nearly sixteen years. That is, he was not surprised by ruling which he did not receive abruptly. He was brought up to be a caliph, and took over when he was thirty-one years old. By that time, he was a mature, aware man, and was given a very good opportunity to administer the affairs of the state, and he remained in office for sixteen years. Were he to be competent, he was supposed to get ready, strengthen the state, make it more awe-inspiring, raise its position, prepare its army, and make it more respected and highly esteemed; otherwise, it was due on him, in case he was true to himself, to leave office for anyone capable of ruling. He, indeed, was not in charge of a family or a tribe; rather he was in charge of an entire nation, a great glorious nation, the best nation to be produced for all mankind.

But the Caliph did neither of both things; he neither made preparations, nor gave up office. Thus, he inevitably had to pay the price; and his people, who accepted him, also had to pay the price. The greater the lost trust was, the higher the price to be paid by the caliph and his people would be; and you would see how large it was!

The state did not run short of the fund necessary for buying or even manufacturing weapons, on the contrary, official stores were packed with weapons. But those weapons either became too old to use, or were very new, even though unused. Unfortunately, no one was ever trained to use them.
Thus, the army of the Abbasid Caliphate became weak and feeble, and unfit to defend even a small emirate, let alone a great caliphate.
This was the state of the Caliph in Baghdad!

What about the government of Baghdad? No doubt, both the ruler and his retinue were the same. The government was as weak and feeble as the army, consisting of ghosts of ministers, whose main concern was only to collect wealth, expand their authority, dominate people, compete with each other legally or illegally, and bitterly clash with each other for (such trivial things as) a house or an office, or even a slave-girl. This collapsing cabinet was headed by a treacherous vizier, who sold the state and the people, and took as allies the enemies of the Ummah, and took as enemies the people of the Ummah. This cabinet was, indeed, working against the souls and property of the Muslims. The relationship of the cabinet members with the Muslims whom they were supposed to protect was not the relationship of a brother with his brother, in so much as the relationship of masters with their slaves.

https://www.islamstory.com/en/artical/20764/too-weak-caliph