A world without a caliphate!

We ask Allaah, the Almighty to bring all the Muslims together under the flag of one caliphate, following the Prophetic method.
In the wake of the fall of Baghdad, a strange belief started to circulate among the Muslims, and captured the attention of a lot of Muslims so much that it became the topic of the hour. It spread among the people very quickly. That is because the people are accustomed to listening to anything that is strange.
They believed that the emergence of the Tatars, the defeat of the Muslims, and the fall of Baghdad were but portents of the Day of Judgment; and that Al-Mahdi Al-Muntathar would appear soon to lead the Muslim armies and emerge victorious over the Tatars.

In my view, it is true that Al-Mahdi will appear one day, and that Christ, May Allaah Exalt his mention, will also descend one day, and that the Hour will be established. All those things, as we know, will certainly take place. But no one knows when exactly all of this will happen. Allaah, the Almighty Says (what means): {People ask you concerning the Hour. Say," Knowledge of it is only with Allaah. And what may make you perceive? Perhaps the Hour is near."} [Quran 33:63] 

Why do such calls only appear at the time of defeat and downturns?
The only reason is that the people were so completely frustrated that they had doubt about achieving any possible victory over their enemies by themselves alone. The people became certain that they had no power to face Hulagu and his soldiers. So, they looked for an easier solution; let it be even Al-Mahdi. "Then, let us wait until Al-Mahdi appears, and it is only at this time that we would fight along with him. But before that, we could not fight. Anyway, let us watch the situation remotely! Let us lie in wait for a miracle to happen!"
What frustration, hopelessness and despair! But none of those is a characteristic of the believers: {"Indeed, no one despairs of relief from Allaah except the disbelieving people."} [Quran 12:87]

What makes you know that you will live till Al-Mahdi appears? You should know that if you die before his emergence, you will be called to account by Allaah, the Almighty for your deeds, not for your life at his time. What makes you think that even if Al-Mahdi appears, you will be one of his soldiers? No doubt, his soldiers will be chosen by Allaah, the Almighty; and this choice will not be random, Allaah Forbid! It will be in accordance with faith and deed. We ask Allaah, the Almighty to Use us in service of His religion.
That was the Islamic situation after the fall of Baghdad.
What were the circumstances of the Christian world?

All parts of the Christian world were overjoyed, as expected. As I have previously mentioned in the beginning of this book, there were three superpowers in the world in the 7th century A.H. the Islamic world, the Christian world and the Tatars. The wars between both the Islamic and the Christian worlds were at their peak. This Tatarian strike caused the Islamic world extreme pain, and, assuredly, renewed the Crusader aspirations to control Egypt and Shaam.
What delighted the Christians more was that they cooperated with the Tatars in this last campaign. Both kings of Armenia and the Kurg, and the emir of Antioch joined the Tatarian party. They were more joyful because the Tatars, for the first time in their history, were true to their treaties. They had already promised the Christians not to harm them in Baghdad, and they did accordingly. Moreover, Hulagu gave Makika; the Christian Patriarch, lots of precious gifts, and one of the great palaces of the caliphate, and appointed him one of his advisors and a member in the new ruling council, and one of his close men whose opinions were highly appreciated in Baghdad.

Of course, this led the Christians to claim that the Tatars were the instruments used by Allaah to take revenge on the enemies of the Christ, May Allaah Exalt his mention, i.e. the Muslims, although a few years ago, the Tatars killed the Christians themselves in Europe. But weak memory seems to be characteristic of the Christians. The Crusaders overlooked the crimes committed by the Tatars against the Christians as long as the Tatars now are killing the Muslims; just as the Christians, in those days, overlooked the atrocities committed by the Jews against them in the past, as long as they are now killing the Muslims. History always repeats itself.

The same words said by the Christians about the Tatars and their gloating over the misfortune of the Muslims occurred once again in the wake of the fall of Granada in Andalusia. Exalted be Allaah! There is an amazing similarity between the fall of Baghdad and the fall of Granada, which gives very great importance to the study of history, since the events of history happen again and again in a way that is beyond human imagination.

https://en.islamstory.com/en/artical/20761/strange-belief-among-muslims