The province of Gallic Poitou was a district of Aquitaine during the Roman occupation of northern Europe, from about 50 B.C.. The region was conquered by the Visigoths in the 5th century. The Franks overran the area in 507 and it was included in the duchy of Aquitaine in the 8th century. In the 8th century Charlemagne gave the kingdom of Aquitaine to his son Louis le Pieux. Louis passed this possession to Pepin 1st who held it from 838 to 848. From 848 to 855 it was ruled by Charles le Chauve. Charles l'enfant was ruler from 855 to 867. In 867 it was ruled by Louis II le Begue. In 879 Louis III passed the kingdom on to his brother Carloman and it was elevated to a Duchy. It returned to the house of Aquitaine in the 10th century and was established under the house of Poitou at its capital in Poitiers. Poiters had been Christianized in the 3rd century. It's first Bishop was St.Hilaire which became one of the religious places of Gaule.
From the 10th century Poitou was the core of Aquitaine. Aquitaine was made a duchy in the 10th century. Eleanor, daughter of William X of Aquitaine, married King Henry II of England thereby carrying with her all the considerable French estates of Poitou, and the whole of Aquitaine and many to the south. This act, perfidious in the mind of the French King, would set the stage for the conflict between England and France for the next three or four centuries. The contentious occupation was the base for the Hundred Years War. Poitou remained in French hands until 1202 under the leadership of Philippe Auguste. It was re-united to the French Crown in 1271 by Philippe III. Poitou returned to English domination until the treaty of Brittany in 1360, when it was again returned to France by Du Gueschin in 1372. Charles VII of France made Poitiers one of the official court residences on his tour through his domain. He founded the government and a university in the city in 1432.