The Greek folk song "To Kastro tis Orias" (The Castle of the fair maiden) which recounts the tale of the "turkish" seige of a castle is theorised to recount the events surround the sack of Amorium in Phrygia in 838 AD by the Abbasid Caliphate. According to historical records, the fortifications were breached and the city was sacked after a Byzantine garrison commander made a secret deal with the beseigers. Over the centuries, this treachery was retold in many ways. The most common retelling in the folk songs is of a "turkish" soldier who disguised himself as a monk or pregnant woman, and tried to gain the sympathy of a "fair maiden" and thus open the gates to the castle to let the poor individual in. As soon as the gate was opened, the beseigers took the opportunity to rush in and capture the castle.
The lyrics and style of the song vary from region to region (versions from Albania and as far as Cappadocia have been recorded). You can listen to them on this very valuable youtube playlist.