Gabriel identified the ram with the two horns as Media and Persia (cf. Daniel 8:3-4), not just Media as many liberal interpreters insist because of their second-century composition hypothesis. The goat, here further described as shaggy, represents Greece (cf. Daniel 8:5-7), not Persia as many liberals contend. The large horn on the goat is the first king of Greece, namely, Alexander the Great. The four kingdoms that arose to replace Alexander when he died were Macedonia and Greece, Thrace and Asia Minor, Egypt and Palestine, and Syria and Persia (cf. Daniel 8:8). [source][source][source]
"Most [1] expositors agree that Daniel 8:20-22 have been fulfilled completely in history in connection with the Medo-Persian and Greek empires and the four divisions following Alexander the Great. The exegetical problems arise in the passage which follows." [2][source]