Bubonic plague reaches Constantinople. At least 230,000 people die in the city and perhaps two million in the empire.
This Justinian plague undermines emperor's attempts to renew Roman glory through conquests. This plague becomes pandemic and continues to castigate Europe, the Middle East, and northern Africa for the next 200 years, until 750.
Professed receiving revelations from God, which were recorded in the Qur'an, the basis of Islamic theology, in which he is regarded as the most important prophet.
Holy Roman Emperor Henry IV walks to Canossa where he stands barefoot in the snow to beg forgiveness of the Pope for his offences, and admitting defeat in the Investiture Controversy.
This helps establish Papal rule over European heads of state for another 450 years.
Second Crusade. The Second Crusade was in retaliation to the fall of Edessa, one of the first Crusader States founded in the First Crusade. It was an overall failure.
This was the first Crusade to have been led by European Kings.
Third Lateran Council. Limited papal electees to the cardinals alone, condemned simony, forbade the promotion of anyone to the episcopate before the age of thirty.
Third Crusade. This follows Saladin uniting the Muslim world and recapturing Jerusalem. Despite managing to win several major battles, the Crusaders did not capture Jerusalem.
Spanish Christians succeed in defeating the Moors in the long Reconquista campaigns. By 1248, only the small southern kingdom of Granada remained under Muslim control.
Fourth Lateran Council. Dealt with transubstantiation, papal primacy and conduct of clergy. Proclaimed that Jews and Muslims should wear identification marks to distinguish them from Christians.
The Black Death ravages Europe for the first of many times. An estimated 20% - 40% of the population is thought to have perished within the first year.