Book of Deuteronomy have given various answers to the problem. The Deuteronomistic history theory is currently the most popular (Deuteronomy was originally just the law code and covenant, written to cement the religious reforms of Josiah, and later expanded to stand as the introduction to the full history); but there is an older theory which sees Deuteronomy as belonging to Numbers, and Joshua as a sort of supplement to it. This idea still has supporters, but the mainstream understanding is that Deuteronomy, after becoming the introduction to the history, was later detached from it and included with Genesis-Exodus-Leviticus-Numbers because it already had Moses
Book of Leviticus sin and guilt offerings, provide the means to gain forgiveness for sins (Leviticus 4–5) and purification from impurities (Leviticus 11–16) so that God can continue to live in the Tabernacle in the midst of the people. Scholars generally agree that Leviticus developed over a long time and that it reached its present form in the Persian period (538–332 BC). The English name Leviticus comes from the Latin "Leviticus," which is in turn from the Greek Greek Λευιτικόν, "Leuitikon", referring the priestly tribe of the Israelites, “Levi.” The Greek expression is in turn a variant of the rabbinic Hebrew "torat kohanim",