Jamieson, Fausset and Brown on Genesis 42:5

5. the famine was in the land of Canaan--The tropical rains, which annually falling swell the Nile, are those of Palestine also; and their failure would produce the same disastrous effects in Canaan as in Egypt. Numerous caravans of its people, therefore, poured over the sandy desert of Suez, with their beasts of burden, for the purchase of corn; and among others, "the sons of Israel" were compelled to undertake a journey from which painful associations made them strongly averse.