I think cultures should look something like this:
View attachment 1215978
Rusyn: represents Carpathian dialects in Ruthenia and Ruthenians within Hungary. No primary tag.
Red Ruthenian: represents Halych-Bukovina dialect group, the Red Cities, the lands controlled by Halychyna in Ukraine, and the lands influenced by Halychyna in Ukraine and Moldova. Primary tag: Halychyna.
Volhynian: represents Volhynian dialect, Duchy of Volhynia, and historical Volhynia region. Primary tag: Volhynia.
Podolian (optional): represents Podolian dialect and historical Podillia region. Primary tag: Podillia.
Dnipro Ruthenian / Ukrainian: represents Central Ukrainian dialect and part of the lands controlled by Kyiv. Primary tag: Kyiv, additional tags: Pereyaslav.
Polesian: represents two Polissian dialects, Turov-Pinsk, the former control Volhynia in Belarus, and may include parts of Southeastern Belarus where no other dialect is appropriate. Primary tag: Turov, additional tags: Pinsk, Slutsk.
Black Ruthenian: represents the Black Ruthenia region. Primary tag: Slonim.
Severian: represents Eastern Polissian dialect and the land controlled by Chernihiv. Primary tag: Chernihiv, additional tags: Rylsk.
Polatskian: represents the former extent of the Duchy of Polotsk and some Belarusian language extent in western Russia. Primary tag: Polotsk; additional tags: Vitebsk, Minsk, Drutsk.
Smolenskian: represents the Principality of Smolensk and the former extent of what we might now call the transitional Russian-Belarusian dialects. Primary tag: Smolensk, additional tags: Toropets, Mstislav, possibly others.
White Ruthenian (optional): this would represent the parts of Belarus not controlled by Polotsk, Chernihiv, or Smolensk, not part of Black Ruthenia, and not speaking a Polissian dialect. Its extent is rather arbitrary, so I'm not really in favor of it, and it's probably better split between Polatskian and Polesian. No primary tag.