6/ The modern borders were (with a few minor tweaks) set after WWII, with Poland 🇵🇱 transferring a large chunk of territory in the east to the Soviet Union (now Lithuania 🇱🇹, Belarus 🇧🇾, and Ukraine 🇺🇦) and gaining German territories in the west.
The border with Germany 🇩🇪 was not fully finalized until 1992 following German reunification.
https://en.wikipedia.org/wiki/German%E2%80%93Polish_Border_Treaty
7/ The different historical backgrounds of the various regions of modern Poland 🇵🇱 continues to have cultural and political implications today.
Some commentators refer to "Poland A" and Poland B" roughly corresponding to the formerly German parts of Poland (A) and the formerly Russian and Austrian parts (B).
https://en.wikipedia.org/wiki/Poland_A_and_B
here is a map of 2020 election results which roughly mirrors the divisions from a hundred years previously
#geoweirdness