The book of Joshua has two main components, likely by different authors. The first describes the conquest of Canaan, and the second describes its settlement. The book is an amalgam of many different sources from many different authors over centuries. For example, ch. 6-11, about the conquest, was written near the end of the 8th century BC in Judah, when the country was under Assyrian country. The Book of Settlement (ch 13-21) uses various administrative documents from the end of the 7th century.
In terms of historical accuracy, Joshua directly contradicts archeological data. Joshua claims that the Israelites conquered the entire region of Canaan, massacred its population, and burnt its cities to the ground. Archeology suggests that the Israelites were indigenous Canaanites who first settled in the relatively empty central hill country. There is no widespread destruction at the end of the late Bronze age, when the conquest would have occurred, and at least two of the cities in Joshua–namely Ai and Jericho–did not even exist at the time.
Joshua 1-4: After the death of Moses, the LORD commands Joshua to lead the Israelites across the Jordan. The Reubenites, the Gadites, and the half-tribe of Manasseh go with them as troops, even though their land is on the eastern side of the Jordan. Joshua sends two spies to Jericho, who stay at a local prostitute’s house. Because the prostitute hides them from the king of Jericho, and because she realizes God will allow the Israelites to massacre Jericho’s population, she begs them to spare her family, and they agree. Shortly afterwards, the Israelites set off from Shittim to cross the Jordan. The LORD blocks the river, turning it into dry land for them to cross. As they were crossing, the chieftain of each tribe picks up a stone from the middle of the Jordan. They arrive at Gilgal by the first night, and set the stones up at their camp to remind future generations of the crossing of the Jordan.
- These chapters are consciously following the model of Moses. Just as Moses addressed the Transjordanian tribes about their obligation (Numbers 32), so does Joshua (1:12-15). Just as Moses sends spies (Num. 13), so does Joshua. Moses parts the Reed Sea, while Joshua parts the Jordan.