In the Middle Ages there was a big country in Europe between France and German kingdoms, Burgundy. What language did they speak there? Were they more German or French in origin?
The Burgundians were originally a Germanic tribe that settled the area that became known as Burgundy. Because it was so deeply in the heart of "French" territory, it adopted the French language and culture as soon as the Franks started pushing back the Saxons under King Charles Martel, and his grandson, Charlemagne. After the death of the latter, it represented the middle of the three "Frankish" kingdoms. Thereafter, it maintained ties to France, with their rulers typically being cousins or in-laws of French kings.
The two countries' paths threatened to diverge during the 100 Years' war when Philip, the Duke of Burgundy married the heiress to Flanders, which had rebelled against France, and was allied with England. During the rest of the war, Burgundy's allegiances flipped back and forth, largely depending on who was winning.
Even so, friction between Burgundy and France continued, especially when their respective kings died, and their heirs, Charles the Bold and Louis XI took over. In 1477, Charles the Bold rashly went to war against the Swiss over Alsace-Lorraine and lost his life, while the French continued to gobble up Burgundy proper, town by town. His daughter and heiress, Marie, married Maximilian I of Austria, and managed to carry the "Netherlands" (including modern day Belgium) into the Hapsburg empire, but Burgundy proper was lost to the French in the ensuing chaos.
Burgundian and Franc-Comtois dialects of the langues d'oïl was certainly spoken by a vast proportion of subjects. Some form of Flemish (which was called Diets at the time) was spoken in the Low Countries as well. Burgundy eventually split into Belgium, the Netherlands, and France with the core of Burgundy remaining in France.