How and when was the name "Pays de Galles" constructed in French?

Question

I am asking this in relation to this Linguistics question: When was the name of Wales first mentioned in Romanian, and in which form?.

At the same time I have posted this on English SE: Etymology of the name Wales/Welsh in modern English: which one is the basic term?

To that I have an answer: in modern Norman/English the name of Wales is based on the name of the people, because initially WAS the name of the people.

What is the origin and the meaning of the name "Pays de Galles" in French?

• Is it a transcription of the English term Wales - as in Prince of Wales?

• Did Galles in French originally mean "the people" or "the territory"?

• Is it already attested in Medieval Latin and translated from that into French?

• At what time was it first attested and in which context?

Although I am interested in the term for the Welsh people in French, I am mainly asking about the terms "Wales" and "Prince of Wales" in French.

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Anticipating my own answer, I make the following suppositions:

• "Pays de Galles" is based on the form of the title "Prince de Galles", which preceded it. Wikipedia says that

Owain Gwynedd (1100–70) of the Aberffraw line was the first Welsh ruler to use the title princeps Wallensium (prince of the Welsh)... Owain Gwynedd's grandson Llywelyn Fawr (the Great, 1173–1240), wrested concessions through Magna Carta in 1215 and receiving the fealty of other Welsh lords in 1216 at the council at Aberdyfi, became the first Prince of Wales. His grandson Llywelyn ap Gruffudd also secured the recognition of the title Prince of Wales from Henry III with the Treaty of Montgomery in 1267.

but looking closer we find that

the future Edward II, was born at Edward's new castle at Caernarfon in 1284. He became the first English Prince of Wales in 1301

• 1301 is the date after which that title entered the English language. At that date it read "Prince of the Welsh people", and only after that date could "Wales" become the name of the country.

• @Laure SO - Écoute-nous made very interesting comments under this question, pointing out that the French terms for Welsh existed well before that date as early as 1170-1176: 1170 adj. fém. galesche (Chr. de Troyes, Erec et Enide, éd. M. Roques, 5321); 1176 adj. et subst. galois (Id., Cligès, éd. A. Micha, 1437 et 1794). **Dér. de Galles, région de l'ouest de la Grande-Bretagn**e; suff. -ois*. Fréq. abs. littér. : 31. - here.

• The last part of the above (Dér. de Galles), is problematic; if Galles as name of the country is a transliteration from Wales (after 1301), then the French terms from Chrétien de Troyes cannot derive from that French name; in the linked source the French terms galesche/galois (noun and adjective) of 1170-6 are said to be a derivation of Galles, a region of the Great Britain: either this is not true, or these old French terms for Welsh people are derivations from Galles, but that "Galles" didn't mean the region or the country, but the very people (just like in the English etymology from this answer by Bilkokuya)

here:

 Latin > Old German          Old/Saxon English      Anglo-Norman/Modern English
 Before 500 BC               Before 1066            After 1066           After 1301
 ...................................................................................
 Volcae -> Walhaz (people) -> Wælas (people)     -> Wales (people)     -> Wales (country)
                           -> Wælisc (adjective) -> Welsh (adjective)  -> Welsh (people & adjective)

The Old English Wælas meaning the Welsh people had as adjective Wælisc. The first evolved into the Anglo-Norman noun Wales (name of the people, not of the country — there wasn't one), and the latter into Welsh (adjective, not name/noun). Maybe that the terms entered French at this point - before the creation of the title Prince of Wales - like so:

 Old/Saxon English      Anglo-Norman/FRENCH          FRENCH                           FRENCH
 Before 1066            After 1066                 Before 1301                        After 1301
 ......................................................................................................
 Wælas (people)    -> Wales/Galles(people) ->------------------------------------> Galles (country)   
                                           -> Galois/fem.galesche (people+adj.) -> Gal(l)ois (people+adj.)
 Wælisc (adjective) -> Welsh 

• The above is related also to the question whether in Pays de Galles: is "Galles" a plural?

• That question was triggered after a comment by @Papa Poule indicating another CNRTL source: here - click third tab "GALLES, subst. masc. plur." — look for Galles, subst. masc. plur.Synon. de Gaulois.Les Galles (...) avaient les pieds fort plats (Senancour, Obermann, t. 1, 1840, p. 100). which shows Galles as a synonym of Gauls (!!!) and throws a new light on my old problem about Wales in Romanian.

Answer 1

As far as the "Galles" part goes, a group called the Gauls emigrated from near England to what is now called France, so the derivation of "Gallic" and related words as used today stems from there.