Complex sentence: Thebez was ruled by the Israelite King Abimelech of Shechem, and when the people of Shechem (at that time a Canaanite city) revolted against him, Thebez joined the revolt.
Split into simpler sentences: Thebez was ruled by the Israelite King Abimelech of Shechem. When the people of Shechem (at that time a Canaanite city) revolted against him, Thebez joined the revolt.