Map: https://upload.wikimedia.org/wikiped...e_Spis1910.png



Map of Polish-speaking population in 1910:

https://commons.wikimedia.org/wiki/F...olacy_1910.png

^^^ Superimposed on the map showing:

Yellow line - border of the Duchy of Cieszyn in the 1500s
Blue line - state border from the 5th of November 1918
Red line - state border from the 10th of December 1938

Political borders: http://edus.ibrbs.pl/wp-content/uplo...12-korekta.jpg



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Compare also with the map of languages of Austria in 1910:

http://i.imgur.com/AQKwaCL.jpg



https://www.reddit.com/r/MapPorn/com...910_2785x2197/