When we visited M. Lezeau he told us of the assumed date of our granary - 13th century.
Preuilly was part of the Angevin lands belonging to King John (yup - the evil king John of the Robin Hood tales) who subsequently lost a lot of his holdings in France after the Battle of Bouvines in 1214. I thought M. Lezeau said the granary was built as a result of John losing the battle and needing to raise funds (via taxes) for a campaign to regain the lands, but it appears it may have been Phillip II of France who did the tax thing, because winning at Bouvines gave him control of Anjou and Touraine.*
Also in 1214, the Emperor of China surrendered to Genghis Khan, and in a completely unrelated incident, Oxford University received its charter. Other people who were kicking around at the time include Saint Francis of Assisi, and King Alexander II of Scotland.
What is equally amazing is what the building possibly predates; the Magna Carta, the birth of Marco Polo, the founding of the Dominican Order, the Black Death, and the brewing of Budweiser Budvar beer in Bohemia. The last two are not connected.
If you're having problems with the concept, this highly detailed timeline may help:
*Apparently Susan realised this all along. I obviously wasn't listening properly