I was looking at a map of France back when Henry the eighth was the king of England and there's a small piece of land in France which isn't labelled within France. The land is near Marseilles. I was wondering why was this the case. Do any of y'all have an answer?
Could you, by any chance, link the map so we are sure about what we are talking about ?
The territory you are probably talking about is Avignon, which was for a long time part of the Papal States.
The territory is composed of two parts: the city of Avignon, and the Comtat Venaissin (approximately : Venaissian County, though if anyone has a better translation please do provide it), they are adjacent to each other.
The Comtat was property of the Count of Toulouse. Because Alphonse de Poitier who married the daughter of the Count of Toulouse died in 1271 withouth any direct descendants, the domain passed on to the king of France Philippe III, who gave it to the Holy See (though some sources say that it was given directly by Alphonse de Poitier). Clement V found shelter there after having fleed Rome in 1309.
Meanwhile, the city of Avignon was bought in 1348 for 80 000 golden florin from queen Jeanne. Until 1376, when the Pope manage to come back to Rome, seven different supreme pontiffs ruled from Avignon.
Those lands were, until the French Revolution, generally exempt of military service and taxes. The two territories are annexed by France on the 14th of september 1791, it is one of the first exemple of the right of the people to self determination, most of the population wanting to join France.
It is only in 1814 that the Pope would recognised the lost of his territories.
Side note here: Avignon is a really nice city, I recommend highly a visit to anyone who has the chance
Source: Alain Maureau, "Avignon et Comtat Venaissin", Encyclopaedia Universalis