The first book after the Pentateuch in the Bible is Joshua.
The Pentateuch consists of Genesis, Exodus, Leviticus, Numbers, and Deuteronomy—the first five books of the Hebrew Bible and the Christian Old Testament. Joshua follows Deuteronomy and begins the biblical narrative of Israel's entry into Canaan after the death of Moses.
The book is named for Joshua, Moses' successor and the leader traditionally associated with the conquest and settlement of Canaan. Its opening chapters describe the crossing of the Jordan River and the capture of Jericho. Later sections outline the distribution of the land among the Israelite tribes.
The exact boundaries of the book's authorship and historical interpretation are debated by scholars, but its position in the biblical sequence is not. In Jewish tradition, Joshua is the first book of the Nevi'im, or Prophets. In most Christian Bibles, it is the first historical book after the five books of Moses.
A common mistake is naming Judges, which comes immediately after Joshua rather than immediately after Deuteronomy.