Complex sentence: Later, when Lithuanians were seeking their independence, Russians thrown in an idea of Polish autonomy in Western Vilnius region, and this attributed to the fact that all Polish-majority areas voted for Soviet Communist party candidates.
Split into simpler sentences: Later, when Lithuanians were seeking their independence, Russians seeded an idea of Polish autonomy in Western Vilnius region. This attributed to the fact that all Polish-majority areas voted for Soviet Communist party candidates.