Multiple Arabic historical sources describe a mid-8th century CE earthquake affecting al-Massîsa (aka Masisah aka Mamistra aka Mopsuestia), a fortified frontier town on the Djihân (Pyramus) River in Cilicia. According to Ibn al-Athir, an earthquake in the year A.H. 140 ( 25 May 757 - 13 May 758 CE) weakened the surrounding walls of the city, leaving its already sparse population vulnerable. In response, the Abbasid Caliph al-Mansûr (r. 754–775 CE) ordered the reconstruction of the settlement under Djibrayl b. Yahya. The fortifications were rebuilt, a large mosque was constructed, and labor was mobilized, including the wages of one thousand workers. The rebuilt city was renamed al-Maʿmûra, “the well-built,” reflecting this phase of recovery and investment. A similar tradition is preserved by Kemal ad-Din (Ibn al-ʿAdîm), who likewise attributes seismic damage to the year A.H. 140 ( 25 May 757 - 13 May 758 CE), noting that a suburb of al-Massîsa “suffered from the earthquake.” A third apparently anonymous account, preserved via Le Strange (1905:130-131), places the destruction earlier, in A.H. 139 ( 5 June 756 to 24 May 757 CE), stating that al-Massîsa was “partially destroyed by earthquake” before being restored by al-Mansûr. It is plausible that the seismic damage described resulted from the March 756 CE By No Means Mild earthquake.