Complex sentence: The first two waves consisted mostly of criminals or political prisoners; however, the most recent influx of North Korean workers, which began under the government of Vladimir Putin, is composed of volunteers seeking to escape unemployment and poverty at home.
Split into simpler sentences: The first two waves consisted mostly of criminals or political prisoners. However, the most recent influx of North Korean workers, which began under the government of Vladimir Putin, is composed of volunteers seeking to escape unemployment and poverty at home.