Original: However, the figure of 230,000 dead is based on a historical conflation of this earthquake with earthquakes in November 1137 on the Jazira plain and the large seismic event of 30 September 1139 in the Azerbaijani city of Ganja.
Simplified: However, the number of dead comes from a combination of this earthquake with earthquakes in November 1137 on the Jazira plain and 30 September 1139 in Ganja, Azerbaijan in historical records.