Zengid dynasty
In 1128, Aleppo became capital of the expanding Zengid dynasty, which ultimately conquered Damascus in 1154. In 1138, Byzantine emperor John II Komnenos led a campaign, which main objective was to capture the city of Aleppo. On 20 April 1138, the Christian army including Crusaders from Antioch and Edessa launched an attack on the city but found it too strongly defended, hence John II moved the army southward to take nearby fortresses. On 9 August 1138, a deadly earthquake ravaged the city and the surrounding area. Although estimates from this time are very unreliable, it is believed that 230,000 people died, making it the sixth deadliest earthquake in recorded history.