Three books of the Bible cover this time period: Esther shows us those who stayed in Babylon, Nehemiah describes rebuilding the wall (external), and Ezra describes rebuilding the temple (internal). We focus on Ezra in order to get the internal right before we take on the external projects in the future. Ezra 3 should be our roadmap as we focus on God first (worship), the get to the work of witnessing to the world.