20 The ram which you saw, that had the two horns, they are the kings of Media and Persia.
Daniel 8:20 Cross References - WEB
Daniel 8:3
3 Then I lifted up my eyes, and saw, and behold, there stood before the river a ram which had two horns. The two horns were high; but one was higher than the other, and the higher came up last.
Daniel 11:1-2
1 “As for me, in the first year of Darius the Mede, I stood up to confirm and strengthen him.
2 “Now I will show you the truth. Behold, three more kings will stand up in Persia; and the fourth will be far richer than all of them. When he has grown strong through his riches, he will stir up all against the realm of Greece.