Canaan of course represents the promised land that is "overflowing with milk and honey," and the land that God gives to his people, the Israelites. However, as a significant part of the first few books of the Old Testament go to show, this land is not just empty and waiting to be possessed by the Israelites. A number of tribes have occupied it and are very strong and difficult to defeat, as the Israelites believe. The names of these tribes can actually be found if we turn back to the Book of Genesis, which details the Table of Nations and the origins of the first tribes that filled the earth. In particular, consider Genesis 10:15-19:
Canaan was the father of Sidon his firstborn, and of the Hittites, Hebusites, Amorites, Girgashites, Hivites, Arkites, Sinites, Arvadites, Zemarites and Hamathites. Later the Canaanite clans scattered and the borded or Canaan reached from Sidon towards Gerar as far as Gaza, and then towards Sodom, Gomorrah, Admah and Zebolim, as far as Lasha.
Thus we can see the origins of the lands of Canaan and the names of the various tribes that populated it, all descending from Canaan himself. The Israelites have to face many struggles and trials and battles before finally occupying the land that they felt was given to them by God.