The Hebrews became a nation forty years previously, when they came out as a people from Egypt, but this is the foundation of Israel as a nation with its own land. Modern arguments against this are irrelevant for any Christian, because what God says is supreme – not what men say.
Penned by Joshua, some suggest this Book (Sefer Yĕhôshúa) was written after the events spoken of, by a prophet as historian. Nevertheless, it is completely accurate, given to men by God through direct inspiration. It is the first book of Deuteronomistic history, covering the time between the conquest of Canaan to the Babylonian exile.
This looks at the beginning of Israel-proper, the defeat of enemies, and the dividing-up of the land between the 12 tribes. ‘Scholars’ claim that what is found in the Book is much later than it suggests. Readers should be suspicious of this claim, because it is a typical way to dismiss the authenticity and authority of scripture.
Rabbinical books put the name of Joshua to the Book and I see no problem with that – God can give a man today information pertaining to long ago, and the far future, as well as concerning the present. Atheists and unbelieving theologians tend to cast aside the divine. As believers we must not be tempted to follow these deceptions. On the other hand, there might have been multiple writers. If so, each was divinely inspired to write what they did.
Joshua assisted Moses, who handed over leadership to him, after God refused to allow Moses to enter the Promised Land. Joshua was named Hoshe’a, of the tribe of Ephraim, and was born in Egypt. The name Joshua/Yehoshu’a was given to him by Moses. In Numbers we find him mentioned as one of the 12 spies who toured Canaan to gather intelligence for Moses. He lived to age 110 during the Bronze Age.