The European knights took Jerusalem in 1099. Why did the Byzantine emperors fail to do this before?

After the death of Sultan Melik Shah (1092), the power of the Seljuk sultans split, strife broke out in it, which weakened the resistance of Muslims to Christians.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.