Things in Europe move. I keep forgetting that, and so my mental map lets me down. I couldn’t find Saxony. It had to be there. It was in his title, but where was it? I’d left Saxony over in the east, where it’s supposed to be . . . in the modern country of Germany. That’s not exactly where “Saxony” could be found in 1100. Oops.
Today, when we use a place name, it usually refers to a specific state, province, nation-state, or location. “Alberta” is a fixed spot on the map of Canada, for example. Especially for Americans, France, Germany, Italy, Canada, Texas, those are all places with a set and fixed location, in saecula saeculorum, amen. OK, those of us who grew up in the Cold War are aware that countries split (Czechoslovakia) or reunite (Germany). For people who studied the 20th Century, countries appeared and borders could be briefly fluid (The Austro-Hungarian Empire became: Austria, Hungary, Romania, Czechoslovakia, Poland, Ukraine, Croatia, Slovenia, and a bit of Yugoslavia). But things don’t move all that much, just get parceled out and redistricted. You know, like Congressional districts in the US every ten or so years.
At this point, my European, British, and Medieval historian readers are laughing mightily at the innocence of a Yank abroad. Saxony was a descriptor loooooong before it became a specific region of a country called Germany. Saxons moved into a swath of Central Europe in the 300s or so, give or take, maybe later. “Here be Saxons” was for the Romanized peoples of the south akin to “Here be Dragons.” Just not always as friendly as dragons. Charlemagne dealt with them, several times in fact. His successors, and the later Ottonians, dealt with them farther to the east as they pushed the Holy Roman Empire away from the original Frankish core. Always, Saxony was where you found Saxons.
However, when borders got set for various administrative districts, Saxony as a German Land (state) locked into place. After 1945, for now.

So, there I was, tracing out some things with Frederick Barbarossa and his peers, and looking at the push to settle northern and eastern areas with cities and people, and to establish trade. This is all 1100-1150 or so. And I was reading about Henry “the Lion” Welf of Saxony and Bavaria. The linkage of the two areas made perfect sense, since they have almost-common borders.
But wait, what the heck’s Henry doing up around Hamburg, and Lüneburg, and that area? That’s not Saxony. Lübeck is certainly not Saxony. Why is he interested in things there, when he’s east and south?
*waits for snickers and eye rolling to stop*
Yes, you guessed it. I know better. I was imposing the modern map on medieval German lands. When I finally found a good map of the area at the time of the events described, I felt more than a little foolish.

Oh. So Henry the Lion had good reasons to be encouraging development of the northern areas, and the development of the Hanseatic League. And that explained why he controlled so much territory for so long (until his ego wrote a check his skills couldn’t cash.)
Places move, in the sense of “regional names associated with places.” Part of modern Saxony had been in Polish lands or claimed by Bohemia, or both at the same time (until the early 1300s and Casimir III of Poland.) Modern Saxony, and Lower Saxony, and Saxony-Anhalt, had Saxons in them, but were not necessarily Welf Saxony entirely. Yes, I thumped my head lightly against the desk. I know better, much better, but the books I’ve been reading don’t have maps in them. [Insert long cartographic rant here]. So I defaulted to modern maps, and went far astray. No excuses, and I kicked myself once I really started thinking about who was where doing what.