Jamieson, Fausset and Brown on Deuteronomy 33:13-17

13-17. of Joseph he said--The territory of this tribe, diversified by hill and dale, wood and water, would be rich in all the productions--olives, grapes, figs, &c., which are reared in a mountainous region, as well as in the grain and herbs that grow in the level fields. "The firstling of the bullock and the horns of the unicorn" (rhinoceros), indicate glory and strength, and it is supposed that under these emblems were shadowed forth the triumphs of Joshua and the new kingdom of Jeroboam, both of whom were of Ephraim (compare Ge 48:20).