Yahweh commands Moses and Aaron to divide the Israelites according to tribe and count the fighting aged men. The total is 603,550. The Levites are counted separately as keepers of the tabernacle.
Exodus 1: The Israelites Oppressed
The generation of Joseph dies. The Israelites grow into a large population under successive Pharaohs. Becoming too large of a population, Pharaoh commands all the Hebrew boys drowned in the Nile at birth.