Information about West Francia.
In medieval historiography, West Francia (Latin: Francia occidentalis) or the Kingdom of the West Franks (regnum Francorum occidentalium) was the western part of Charlemagne's Empire, inhabited and ruled by the Germanic Franks, and forms the earliest stage of the Kingdom of France, lasting from about 840 until 987. West Francia was formed out of the division of the Carolingian Empire in 843 under the Treaty of Verdun after the death of Emperor Louis the Pious and the east–west division which "gradually hardened into the establishment of separate kingdoms (...) of what we can begin to call Germany and France".
West Francia extended further south than modern France, but it did not extend as far east. By the 10th century the rule of its kings was greatly reduced and it did not include Lorraine, Burgundy, Alsace and Provence as well as Normandy which was given to Normans in return for end of raiding. In Brittany and Catalonia the authority of the West Frankish king was barely felt. West Frankish kings were elected by the secular and ecclesiastic magnates, and for the half-century between 888 and 936 they chose alternatingly from the Carolingian and Robertian houses. By this time the power of king became weaker and more nominal, as the regional dukes and nobles became more powerful in their semi-independent regions. The Robertians, after becoming counts of Paris and dukes of France became kings themselves and established the Capetian dynasty.