‘ And Joshua said, “By this you will know that the living God is among you, and will without fail drive out from before you the Canaanites, and the Hittites, and the Hivites, and the Perizzites, and the Girgashites, and the Amorites, and the Jebusites.” '
His emphasis was that they might be aware as a result of what happened that their God was a living God, One Who was there, One Who acted, One Who did wonders. And as they saw what He did there they would realise that this was proof that He would indeed without fail drive out from before them the inhabitants of Canaan.
This idea of ‘the living God' comes from Deuteronomy 5:26. There it was linked to God's revelation of Himself on Sinai. No one knew better than Moses that He was ‘the living God'. He had met Him at the burning bush, experienced His wonders in Egypt, been guided by Him at the Sea of Reeds, and spoken with Him on Mount Sinai. Now Joshua wanted them to know that the God of Sinai was to be seen as among them again, as ‘the living God', the God Who would reveal Himself in action on their behalf..
The seven Canaanite peoples are as mentioned in Deuteronomy 7:1 but not in the same order. They are not simply a repetition of Deuteronomy. ‘Seven' nations, the number of divine perfection, signifies all the peoples in Canaan. See also Joshua 24:11. The terms Canaanites and Amorites were both terms regularly used to describe the general population of the country and the terms were often interchangeable. However there was sometimes some distinction in that often the Canaanites was the term for those occupying the coastlands and the Jordan valley while the Amorites could be seen as dwelling in the hill country east and west of Jordan. And as here they could also be distinguished from other inhabitants of the land.
The Hittites were settlers who had come from the Hittite Empire further north and had settled in Canaan. The Hivites may have been the equivalent of the Horites (see on Genesis 36). Their principal location was in the Lebanese hills (Judges 3:3) and the Hermon range (Joshua 11:3; 2 Samuel 24:7), but there were some in Edom in the time of Esau (Genesis 36), in Shechem (Genesis 34) and in Gibeon (Joshua 9:7). The Perizzites were hill dwellers (Joshua 11:3; Judges 1:4 on) and possibly country peasantry, their name being taken from ‘peraza' = hamlet. This is supported by the fact that they were not named as Canaan's sons in Genesis 10:15 on. The Girgashites were mentioned in Genesis 10:16 as descendants of Canaan, see also Genesis 15:21 and Nehemiah 9:8. They were attested at Ugarit in terms of the names ‘grgs' and ‘ben-grgs'. The Jebusites were the inhabitants of Jerusalem and the hills round about (Numbers 13:29; Joshua 11:3; Joshua 15:8; Joshua 18:16). Thus the population was very mixed and open to invasion and infiltration.