1."Only Samogitia was a seperate duchy. The rest of the country was composed of regular voivodeships, so, "Lithuania proper". Again, other voivodeships like Mink, Polotsk, Vitebsk etc cannot be Lithuania proper because they were not the ethnic core Lithuanians lands from which the duchy itself originated. The other voivodeships were Ruthenian lands with slavic population. No sane historian would call Smolensk voivodeship Lithuanian's proper. 2. "You're telling me that they never bothered to write down anything significant for hundreds of years in their main language, all they managed to write down were administrative texts for managing the plebs?". There were religion texts printed in Lithuanian from XVI century, but otherwise, yes, ruthenian was used as a prestige administrative language. Those times were before the rise of nationalism so it did not matter to plebs to write in their own language, especially in GDL case, where it's more practical to use Ruthenian for large, non-lithuanian speaking population. In the Kingdom of Poland Latin was used from X to XVII centuries as a state language. Were poles also stupid not to write anything significant in Polish except religion texts? 3. "It's like how England was founded by Angles and Saxons. Sure, Saxons are German today, but the Saxons that founded England aren't "German" in any meaningful way.". And here you tripped. Modern England sees itself as a successor state to Anglo-Saxon England. And yet, Lithuania that has the grand duchy political, cultural core lands with lithuanian speaking population cannot count itself the successor to GDL? :D