As I have explained previously, the date of the Exodus was about 1446 B.C. (cf. 1 Kings 6:1).7Israel spent 40 years in the wilderness (Exod. 16:35; Num. 14:33-34). Thus Israel crossed the Jordan River and entered the land about 1406 B.C. The Book of Joshua therefore begins with events in or very close to the year 1406 B.C.
Josephus said the conquest of the land took five years.8However when Caleb received his town of Hebron he said God had promised that he would enter Canaan 45 years earlier (14:10; cf. Num. 14:24). Since God gave that promise 38 years before Israel crossed the Jordan the conquest seems to have taken closer to seven years (ca. 1406-1399 B.C.). The record of this conquest occupies the first half of the Book of Joshua.
When Caleb said these words he was 85 years old (14:10). Joshua appears to have been about the same age as Caleb, perhaps a little younger. Joshua died when he was 110 (24:29). Assuming Joshua was 75 when the Israelites crossed the Jordan River, the amount of time the Book of Joshua spans may be about 35 years.9
The first half of the book (chs. 1-12) covers about seven years. Most of this material, specifically, chapters 1-9, deals with events that probably happened in less than one full year.