The Second Beast
Daniel 7:5 "And suddenly another beast, a second, like a bear. It was raised up on one side, and had three ribs in its mouth between its teeth. And they said thus to it: 'Arise, devour much flesh!'"
The 1st. Beast was the Babylonian Empire, which was conquered by the 2nd Beast (the Mede-Persian Empire) The 4th Persian king was the most powerful and he sent his whole military to attack Greece.
Dan 11:2 And now I will tell you the truth: Behold, three more kings will arise in Persia, and the fourth shall be far richer than them all; by his strength, through his riches, he shall stir up all against the realm of Greece.
Dan 8:3-4, 20 Then I lifted my eyes and saw, and there, standing beside the river, was a ram which had two horns, and the two horns were high; but one was higher than the other, and the higher one came up last. I saw the ram pushing westward, northward, and southward, so that no animal could withstand him; nor was there any that could deliver from his hand, but he did according to his will and became great... The ram which you saw, having the two horns—they are the kings of Media and Persia.
This 2nd Beast (chest and arms of silver, an inferior kingdom) was the Mede-Persian Empire with King Darius as it's first king. It was during this period that King Cyrus sent the Jews back to rebuild the temple of God.
The Third Beast
Dan 7:6 "After this I looked, and there was another, like a leopard, which had on its back four wings of a bird. The beast also had four heads, and dominion was given to it."
The Mede-Persian Empire (ram) was destroyed by the Grecian Empire (male goat). Alexander the great, swiftly (leopard) conquered the whole middle East and reached India in a very short period.
Dan 8:5-7 "And as I was considering, suddenly a male goat came from the west, across the surface of the whole earth, without touching the ground; and the goat had a notable horn between his eyes. Then he came to the ram that had two horns, which I had seen standing beside the river, and ran at him with furious power. And I saw him confronting the ram; he was moved with rage against him, attacked the ram, and broke his two horns. There was no power in the ram to withstand him, but he cast him down to the ground and trampled him; and there was no one that could deliver the ram from his hand."
Dan 8:8 "Therefore the male goat grew very great; but when he became strong, the large horn was broken, and in place of it four notable ones came up toward the four winds of heaven."
After the death of Alexander the Great, the Grecian Empire was broken up into 4 kingdoms under the control of each General.
1. Greece and Macedonia
Gen. Cassander took control of Greece and Macedonia;
Gen. Lysimachus took control of Thrace and most of Asia Minor;
3. Southern kingdom
Gen. Ptolemy took control of Egypt, Israel and Petra.
4. Northern kingdom
Gen. Seleucus took control of Iran, Iraq, Syria, Lebanon (former Persian Empire).
Dan 11:3-4 Then a mighty king shall arise, who shall rule with great dominion, and do according to his will. And when he has arisen, his kingdom shall be broken up and divided toward the four winds of heaven, but not among his posterity nor according to his dominion with which he ruled; for his kingdom shall be uprooted, even for others besides these.