In the fourth aliyah the famine predicted in Pharaoh's dream begins. It was a very grave famine affecting Egypt and many other countries. As planned, Yosef had sufficient stores of food and therefore Egypt had food to eat. Meanwhile Yosef's father Yakov and his other eleven sons were in the land of Canaan.
Although they were not suffering from the famine, nevertheless, Yakov sends all of his sons other than Binyamin down to Egypt to buy food. On the way, it is the brother's intention to look for Yosef, their lost brother, because they regretted selling him. When the brothers get there, they have to go to their brother Yosef to request food, but they don't recognize him because he has grown up to be a man.
The brothers bow down to Yosef, fulfilling Yosef's dream of his childhood.