A little about Knights and Tournaments.

As far as I know, it was created after the First Crusade...

You are absolutely right. The fact is that the reason for the First Crusade was that the Knights were starting to suffer from idleness and boredom; they were no longer interested in tournaments, and they either raided each other or robbed their own peasants for no reason. The Pope could not tolerate such lawlessness, and that's when he came up with the idea of sending all this bloodthirsty horde somewhere far away. And he came up with the idea of creating a crusade in the name of the Holy Sepulcher. The main lure for the Knights was that the Pope said that any knight who participated in the crusade or died in it would be cleansed of all sins and immediately go to heaven, and all the sins of eight generations of that knight's ancestors would also be forgiven. In those days, the Church had a custom (or how else should I put it?) that everyone knew that all the pagan tribes that had heard of Christ but had not accepted Christianity would go to hell. And the noble knights could not allow their great-great-grandparents to suffer in hell, so they gathered their weapons and went on a crusade, and of course, they could also loot a lot and get rich there. Thus, even the poor went from Europe to the crusade in the hope of getting rich.
Thus, the Pope got rid of the restless Knights for some time, and for many years, he got rid of the poor people wandering around Europe, as most of them died in the crusade.
And later, the knights began to unite into orders, so that it would be more convenient to rob the eastern countries.