Background: In the 19th century, the Tsarist Government of the Russian Empire claimed that Ukrainian was merely a dialect of Russian and not a language on its own. The differences were few and caused by the conquest of western Ukraine by the Polish-Lithuanian Commonwealth. However, the dialects in Ukraine eventually differed substantially from the dialects in Russia.
Question: The conquest of western Ukraine by what country altered the language of Ukraine?
Answer:<extra_id_0>.
<extra_id_0> Polish-Lithuanian Commonwealth<extra_id_1>