Moses and Exodus 29

Passover night is over and the Israelites are ready to leave Egypt as the Egyptians bury their dead. They are told to "hurry" and leave, and the Israelites marched out as a victorious army with gold, and silver, and expensive clothing. This was the fulfillment of a promise which God had made to Abram hundreds of years before. The Israelites also took a "mixed multitude" of people with them. Who were they?