Under the leadership of Joshua, God is bringing the Israelites into the Promised Land. What a relief! They are no longer under the yoke of Egyptian slavery. They are now free to worship the Lord without retaliation from the government. They now own their own property and can grow their own crops. The manna from Heaven is no longer necessary.
God is always a God of surprises, and He shows up in the most unexpected places and times and to the people least expecting Him.
Moses is no exception. Moses is a fugitive from justice. He escaped Egypt because Pharaoh had heard that he killed an Egyptian. In the land of Midian he met Jethro, who gave him a daughter in marriage. While Moses is working for his father-in-law as a fugitive from justice in a foreign land, God catches up with him.