A magnitude 7.7 earthquake strikes the Caucasus mountains in the Seljuk Empire, causing mass destruction and killing up to 300,000 people.

The 1139 Ganja earthquake was one of the worst seismic events in history. It affected the Seljuk Empire and the Kingdom of Georgia, in modern-day Azerbaijan and Georgia. The earthquake had an estimated magnitude of 7.7 MLH, 7.5 Ms and 7.0–7.3 Mw. A disputed death toll of 230,000–300,000 resulted…