The Forterre is a small French area of the Burgundy icaunaise partly made up of the canton of Courson-the-Careers. Still little time ago, Forterre was included in the historical area of the Puisaye. But the limits between Puisaye and Forterre are very clear: they are at the place where the layers of Jurassic higher (Forterre) are inserted under those of the Infra-cretaceous (Puisaye).

The denomination " Forterre" , from relatively recent appearance, would come, perhaps, directly of the ground Calcaire of the Jurassic superior who confers on this strong ground an open landscape of large plates where, since the regrouping of the Sixties and the systematic pulling up of the " bouchures" , the cereal culture is dominating and intensive.

The dryness of the ground, which will give names of villages like Merry-Dryness and Lainsecq is only quite relative. Water is quite present, but underground and sometimes resurgent as with Druyes-the-Beautiful-Fountains. The vast marly sedimentary layers of the kimméridjien keep water of the rains which the cracks of limestone portlandien let pass. It is one of these layers which ensures the sources of Courson-the-Careers an important flow.

Like all the grounds of culture, Forterre was increasingly richer than its neighbor the Puisaye. Moreover, this anecdote on the church of Treigny built in 1492 on the limit between the two territories is revealing. This building, which one calls " the cathedral of Puisaye" because of its imposing dimensions for a small village, has two more entries, on the right for the rich person Forterrats who paid an important dîme and the other on the left for Poyaudins which discharged with difficulty this tax in kind intended for the Clergé.

Puisaye and Forterre were associated, recently, in the same territory, the Pays of Puisaye-Forterre.

• the Dr. Robineau-Desvoidy in his “ statistical test on the canton of St Saver ” wrote in 1838:

“Difference in climate, difference in manners. The Forterrat with the ensured step, the face coloured, does not resemble nothing with the inhabitant Puisaye which appears to be supported only with sorrow on its legs, and whose face is almost bloodless. At one all is life, movement, force and health; at the other, any advertisement prostration of the forces, languor, a continual state of deterioration. The man of Forterre is swift, dispos; it would be said that the man of Puisaye cannot walk and that it needs a stick to rest. First is undertaking, active; he likes to leave his country, to walk his trade; the second knows only his fields and its farm… Forterre provides men who, without being of a very-high size, are perfectly members, have the martial air, and do not fear the military exercises: Thury, Fontenoy, are mainly pointed out by the beauty of its conscripts…”.

And as, “It is of Forterre as the communes of Puisaye of the canton of St Saver, and that those of the remainder of Puisaye, receive without delay the recruits of population which cultivate the ground, and which maintain continuity there the inhabitants. Without that this region would not delay to become deserted and uncultivated, since the majority of our natives succumb with time. …”.

“Thury acquires 46 years the so high figure for means of existence term human! few communes of France (if however it is some) can glorifier of a similar longevity. It is in Thury that half of the deaths takes place from 55 to 95 years! and the fifth from 75 to 95 years! …”.