West Francia or the West Frankish Kingdom was a short-lived kingdom encompassing the lands of the western part of the Carolingian Empire that came under the undisputed control of Charlemagne's grandson, Charles the Bald, as a result of the Treaty of Verdun of 843.
The Frankish Empire, the great realm united by Charlemagne that consisted of a large part of Western Europe, was partitioned after a three-year-long civil war between his grandsons (840-843), during which Charles the Bald allied himself with his half-brother Louis the German to dispute the inheritance of his brother Lothair I, the nominal Carolingian Emperor of the Franks and Emperor of the Romans (this had been Charlemagne's title, a title also used much later by the Holy Roman Emperors from Otto I and afterwards).
The Carolingian Empire of the Franks founded by their grandfather lasted only one generation through their father Louis the Pious. His realm, the great demesne which had covered most of Northern Italy (Lombardy), France (excepting Brittany), the Low Countries, and most of modern Austria and Germany, was split after some skirmishing to little effect into East Francia, West Francia or the Western Realm, and Middle Francia. The West Frankish Kingdom is however the precursor of both Medieval France and modern France, though West Francia would have to pass to the less quarrelsome House of Capet before it achieved steady growth and stability.
The Carolingians were subsequently to share the fate of their predecessors: after an intermittent power struggle between the two families, the accession (987) of Hugh Capet, Duke of France and Count of Paris, established the Capetian dynasty on the throne which with its Valois and Bourbon offshoots was to rule France for more than 800 years. After 987, the kingdom came to be known as France, as the new ruling dynasty (the Capetians) were originally dukes of Île-de-France, the region encompassing Paris.