To what does the sin offering testify?

Ezra 6:17 (ESV)

17 They offered at the dedication of this house of God 100 bulls, 200 rams, 400 lambs, and as a sin offering for all Israel 12 male goats, according to the number of the tribes of Israel.

The sin offering of twelve male goats is according to priestly ritual (Leviticus 4:22–26) and testifies to the idea that the twelve tribes have been re-established. Israel is ready to resume its covenantal relationship with the Lord.1 Sin offerings were an admission of past failures and also symbolized the cleansing of the sacred space to set it apart for God.2