In which I seek an historical fact and don't find it

Last week in Portugal I conducted some historical research about Christians under Muslim rule. According to the historian A R Disney, Christian monasteries and nunneries continued to function under Muslim rulers in the 9th, 10th and 11th centuries, and he cites two centres of Christian pilgrimage in the Algarve which were respected by the Muslim authorities.  In search of one of them, a sanctuary of the Virgin Mary, I took the bus to Faro, and was in luck, for prominently displayed in the small municipal museum is a modern tapestry telling the legend of Santa Maria de Faro.  During the years of Muslim rule, Muslims and Christians quarrelled over an image of the Virgin, which for the sake of a quiet life the Christians were obliged to ditch in the harbour. No sooner was the deed done however, than to the distress of the local fishermen all fish disappeared from the sea. Realising their mistake, the Muslims dredged the image up and restored it to its rightful place, whereupon the fishermens’ nets were filled more bounteously than ever before.  This is numbered amongst the miracles of the Virgin. Incidentally, Mary is venerated in Islam, indeed according to Wikipedia is mentioned more times in the Koran than in the New Testament. 

Tapestry in Faro municipal museum. The panels show: a fight, throwing the statue into the sea, empty fishing nets, pulling the statue out of the sea, statue restored on the wall, full fishing nets

I showed the curator the passage in Disney's book (A History of Portugal and the Portuguese Empire) about the shrine to the Virgin, and asked him if any evidence of it has survived. Sadly not. Moreover, whilst he was familiar with the book, he told me that other than the legend, there is no evidence for these events.

Hmm ... history books are full of facts and you can hardly have history without them; but the one and only fact that I've actually checked for myself seems to have evaporated before my eyes.

If I'm back in the Algarve next year I'll dig some more. And I hope I shall be, because I missed out on the museum of dried fruit in Loulé.  A circumstance which when mentioned occasions unaccountable hilarity, but I intend to prove the scoffers wrong.

More about that disputed image

A thought on the dispute between the Christians and Moors over the image of Mary. The legend mentions that the Moors resented the statue, with no explanation offered as to why. It occurs to me that to those who first heard the story no explanation was necessary – for the Moors’ prohibition of images would be too well known to need mentioning, and Mary being a figure of reverence to Muslims would make the Christians’ statue all the more abhorrent.

The source of the legend appears to be an old Spanish poem, or song, translated: “In Faro, there was a statue of the Virgin. It had stood on the seashore since the time of the Christians, and captives prayed to it. Christians called the city ‘Holy Mary of Faro’ because of the statue. The Moors resented this and threw the statue into the sea. As long as the statue lay in the water, the Moors could not catch any fish. When they realised this, the Moors recovered the statue. They placed it on the wall between the merlons [battlements]. Afterwards, the Moors caught even more fish than they had before.”

Note: The poem is “The Moors of Faro who Threw a Statue of the Virgin into the Sea”. It's no 183 in the Cantigas de Santa Maria, a collection of poetry in medieval Galician composed at the Court of King Alfonso X of Castile in the second half of the 13th century. See the Oxford database of Cantigas de Santa Maria. This poem departs from the legend given in the Faro museum, where it's the Christians under duress who threw the statue into the sea, whereas in the poem it's the Moors.

Another note: I've seen medieval Persian depictions of Mohammed, which shows that the detestation of images has not always been a consistent feature of Islam.