Joshua 12:15 lists the defeated kings on the east side of the Jordan River that were conquered under Moses' leadership. This verse serves as a historical record of the victories that God granted to the Israelites as they entered the Promised Land. It highlights the fulfillment of God's promise to give them victory over their enemies and establish them in the land He had promised to their ancestors. The detailed account of the defeated kings demonstrates God's faithfulness in fulfilling His covenant with His people.