How does Leviticus 15 connect to what comes after?

The laws which have been outlined in Leviticus 11–15 serve as the backdrop for the rituals on the Day of Atonement. These rituals were designed to cleanse the tabernacle of the uncleannesses of the Israelites (Leviticus 16:16). Wenham¹ writes, Without these chapters we should be at a loss to know what was the purpose of the ceremonies described in ch. 16.