Complex sentence: The crowd moved on toward the Badlands, the heart of the black residential area, and filled with substandard housing leased at high rates to them, but middle and upper-class people lived here, too.
Split into simpler sentences: The crowd moved on toward the Badlands, the heart of the black residential area. It was filled with substandard housing leased at high rates to them, but middle and upper-class people lived here, too.