Oh, but don't take my word for it! Check the Wikipedia! Check the "Narodowy Spis Powszechny ", the one from 1921 and 1931. Statistics made by the Polish goverment.
Wołyńskie voievodship (1921-1931)
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en.wikipedia.org/wiki/Wo%C5%82y%C5%84_Voivodeship_%281921%E2%80%9339%29
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Ukrainians - 68%Poles - 17%
Jews - 10%
Germans - 2.3%
Czechs - 1.5%
Eastern Orthodox Christian - 69.8%Roman Catholic - 15.7%
Judaism - 10%
Protestants - 2.6%
The rest were tatars and muslims.
Tarnopolskie Voievodship
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pl.wikipedia.org/wiki/Wojew%C3%B3dztwo_tarnopolskie
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Poles - 44.98% in 1921, 49.3% in 1931
Ukrainians - 49.98% and 45.5%
Jews - 4.83% and 4.93%
Germans - 0.17%
Greek Catholic - 59,36% and 54.48%Roman Catholic - 31,35% and 36.65%
Judaism - 9,03% and 8.3%
Protestant - 2825 and 3700 people
Stanisławowskie Voievodship
=================
pl.wikipedia.org/wiki/Wojew%C3%B3dztwo_stanis%C5%82awowskie
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Ukrainians - 68%Poles - 22%
Jews - 7.4%
Germans - 1.1%
Greek Catholic - 74%, 73%Roman Catholic - 14.5%, 16.6%
Judaism - 10.8%, 9.4%
Protestant - 0.8%
Wileńskie Voievodship
=============
en.wikipedia.org/wiki/Wilno_Voivodeship_%281926%E2%80%9339%29
pl.wikipedia.org/wiki/Wojew%C3%B3dztwo_wile%C5%84skie_%28II_Rzeczpospolita%29
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Poles - 59.7%Belarussians - 22.7%
Russians - 3.4%
Jews - 8.5%
Lithuanians - 5.5%
Roman Catholic - 62,5%Eastern Orthodox Christian - 25,4%
Judaism - 8,7% mojżeszowego
Other faiths - 3,4%
Nowogródzkie Voievodship
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In 1931 the Nowogródek Voivodeship was home to about 616,000 ethnic Belorussians, or ~39% of the total population of Polish lands later annexed by Stalin. The number of ethnic Belorussians exceeded the number of ethnic Poles by eight percentage points.[7] Similarly, the Jewish population statistics were inappropriately reduced by about 4% in the actual number of dependants. The chairman of the Polish census statistical office, Edward Szturm de Sztrem stated after World War II that the returned forms might have been tampered with by the executive power, but to what extent is not known.
en.wikipedia.org/wiki/Nowogr%C3%B3dek_Voivodeship_%281919%E2%80%9339%29
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Moral of the story - I was only really wrong about Wileńskie, and that one still had no less than 22% Belorussians. Nowogródzkie numbers are highly controversial. When it comes to facts, saying "LA LA LA I CAN'T HEAR YOU!' doesn't work. The Second Polish Republic (II RP) was a cultural melting pot. I have a hunch you would hate living there. The 0.4% of foreigners Poland currently has is pathetic and... unhealthy.