Two major historical events were to accelerate the development of Bastides in our region : the Crusade against the Cathars at the beginning of the 13th century and the tensions between France and England that began at the end of the same century. 

Raymond VII, the powerful Count of Toulouse, is considered to be the instigator of this development. On the death of his father, Raymond VI, he inherited a few fiefdoms in the Agen region, together with a leaning towards the Cathar cause. But after the terrible repression of the Albigensians by the Crusades of Simon de Montfort and the peace treaty signed at Meaux in 1229, some of the strongholds of the Count of Toulouse were dismantled. In order to maintain his power base after this heavy defeat, he still needed to rely on these strategic positions, which, however, could no longer be fortified. Raymond VII therefore made use of these naturally defensive positions to create open, Bastide villages, such as Puymirol, the oldest of the Lot-et-Garonne Bastides. 
On the death of Raymond VII in 1249, Alphonse de Poitiers, the brother of St.Louis, took possession of the County of Toulouse, as had beeen agreed in the Treaty of Meaux. This wise administrator of the Languedoc was to go on to be the main force in the expansion of the Bastides, having created a total of twenty by his death in 1271. 
His two main objectives were to confirm a Capetian authority which would last, (its limitations in South-West France having been revealed by the Cathar crisis), and to create a front line against the English, who had been occupying the western half of the Aquitaine for a hundred years now. 
After the death of Alphonse de Poitiers, the represntatives of first Philip the Hard1270-1285) and then Philip the Handsome (1285-1314) continued to found Bastides and they were imitated from the end of the 13th century by Edward the 1st of England (Miramont de Guyenne). Thus all along the Franco-English frontier, the Bastides added a military dimension to their economic role. But they only began to be fortified from the beginning of the 14th century, as at Vianne, which has retained its outside walls to this day. This phenomenon intensified up to the official outbreak of the Hundred Years' War in 1337. This disastrous conflict, with its attendant famine and disease, would obviously bring a halt to the creation of new towns. A new climate of insecurity disrupted commercial activity and the most economically weak Bastides disappeared. 

Thus, like all enterprises, Bastides sometimes prospered and sometimes suffered in an unstable geopolitical context. Yet they remain the historical reflection of our region. Some of them have succeeded and become the head of the local canton and even taken on wider administrative responsibilities. Their diversity and the marvellous restorations that many have undergone make some of our Bastides, such as Monflanquin, Villeneuve-sur-Lot, Villeréal and Vianne, unmisssable, whereas others - Le Rayet, Lasserre and Montjoi, for example, - have completely or partially disappeared.