Answer:
SILESIA
Explanation: Millions of Silesians were previously mostly German, later expelled, through ''national verification'' Silesians known as "autochthons" by the Polish communist authorities were they were later given citizenship.
Prussia was an ancient region in present day Europe, it comprises parts of the following countries Germany,Poland,Czech Republic, Russia, Lithuana,Switzerland,Belgium,Denmark.
it was the acquisition of the Silesians during the 18th century around the year 1740 that helped Prussia to be known as a great power.