three ribs
A reference to the three-fold dominion of the second empire, Media, Persia, Babylonia.
devour
That is, Lydia, Babylonia, Egypt, etc.
Related Commentaries of Daniel 7:5
Daniel 7:5
5 And behold another beast, a second, like to a bear, and it raised up itself on one side, and it had three ribs in the mouth of it between the teeth of it: and they said thus unto it, Arise, devour much flesh.