Complex sentence: Eight or nine people lived in a single room and the houses hid backyards full of shanties built of cardboard and flattened kerosene cans, since Black property owners in Sophiatown were themselves poor.
Split into simpler sentences: Eight or nine people lived in a single room and the houses hid backyards full of shanties built of cardboard and flattened kerosene cans. The reason for this being that Black property owners in Sophiatown were themselves poor.