From the plaque:
Shahr-e-Gholghola (“City of Screams”) is a fortified urban site dating from late Sassanian (6th c. AD) through to the Ghorid period (12th-13th CC.). The citadel on this hill site was the heart of the Islamic city of Bamyan following the decline of Buddhism here from the 8th century AD.
Shahr-e-Gholghola is believed to have been destroyed by the Mongols under Genghis Khan, who invaded it in 1221 and massacred all the inhabitants. The site’s name is said to date from this massacre.