Jamieson, Fausset and Brown on Exodus 1:8

8. Now there arose up a new king--About sixty years after the death of Joseph a revolution took place--by which the old dynasty was overthrown, and upper and lower Egypt were united into one kingdom. Assuming that the king formerly reigned in Thebes, it is probable that he would know nothing about the Hebrews; and that, as foreigners and shepherds, the new government would, from the first, regard them with dislike and scorn.