How did the twelve sons become the twelve tribes of Israel and who led them?
Jacob's twelve sons went down to Egypt because of Joseph and the grain. While they and their families were there, they multiplied greatly, and those twelve sons became the twelve tribes of Israel. Moses led them out of Egypt and through the wilderness, and Joshua led them into the land.
Les explains that Israel's origin is often unknown even to longtime teachers. After Abraham received the covenant promise that a nation would come from him, the line continued through Isaac, then Jacob. Out of Jacob came twelve sons, including Joseph. Because of Joseph, those sons and their families ended up in Egypt during the grain crisis. There they exploded in population, and those twelve sons became the twelve tribes of Israel. Moses led them out and through the wilderness, and Joshua led them into the land.