If we include Sheshbazzar (Ezra 1:11), then we have the names of twelve leaders who came up from Babylon. This symbolic number, when used in the context of God’s people is meant to remind us of the twelve sons of Jacob, the twelve tribes of Israel. The twelve leaders coming up from Babylon are representative of Israel in its fullest extent.1
2 They came with Zerubbabel, Jeshua, Nehemiah, Seraiah, Reelaiah, Mordecai, Bilshan, Mispar, Bigvai, Rehum, and Baanah.The number of the men of the people of Israel: