1772 and 1919.
The First Partition of Poland, which the Poles proved incapable of resisting, was decided on August 5, 1772. Two decades later, Russian and Prussian troops entered Poland again and the Second Partition was signed on January 23, 1793. Austria did not participate in the Second Partition. The Third Partition of Poland took place on October 24, 1795, as soon as the Polish Kościuszko Uprising was defeated. With this partition, the independent Polish state ceased to exist.[1]
en.wikipedia.org/wiki/Partitions_of_Poland
so in between the Partitions taking place Poland was still Poland until the had fully taken over by the third Partition.
yes, lets base our findings on facts , between 1772 and 1795 Prior to Polands defeat your ancestors did live in What was called
POLAND until the third Partition and so all we need now is a area Map showing which Partitions were no longer considered Poland
From those dates up until Oct 24, 1795.
but Now it hit me why so many Polish left,, I will use this in my own family history book.
As a result of the Partitions, Poles were forced to seek a change of status quo in Europe.[13][14] Polish poets, politicians, noblemen, writers, artists, many of whom were forced to emigrate (thus the term Great Emigration) became the revolutionaries of the 19th century, as desire for freedom and liberty became one of the defining parts of Polish romanticism.
a Summed up version is : Europe screwed them over!