This is the 9566th most frequent Polish word.
wschodnich
"Eastern."
Here, "wschodnich" functions as an adjective describing "regions," indicating a geographical characteristic.
Jestem zafascynowany kulturami wschodnich regionów.
I am fascinated by the cultures of eastern regions.
In this sentence, "wschodnich" modifies "częściach" to specify the location as being in the east.
Wschodnich częściach kraju występują unikalne gatunki roślin.
Unique plant species occur in the eastern parts of the country.
Here, "wschodnich" is used to describe "miast," referring to their geographic orientation or cultural identity associated with the east.