In the vision he saw a ram being killed by a goat representing the invasion of media and Persia by the Greek empire in 336 b.c.
After the goat conquered in the land its horn was broken off representing the sudden death of a king which was Alexander the great after his establishment of the Greek empire in 323 b.c..
When the great horn was broken off 4 notable horns took its place and it was said that 4 kingdoms would arise after the death of the first king of the Greek empire. This has proven to be the creation of the 4 kingdoms divided from the Greek empire in 275 b.c. from Alexander the great's 4 generals which fought for power until there deaths in 275 b.c. called the wars of Alexanders successors.
The 4 kingdoms of the Greek empire in 275 b.c after the death of Alexander the great in 323 b.c. are
In Daniel chapter 8 13-14 a saint asked when will be the time of the antichrist when he will set up the transgression of desolation, kill the holy people and cast the temple down to the ground? He was given the answer that it would be 2300 days for years until the time of the antichrist kingdom and the end of the world.
This Gives an estimated time for the arrival of the Antichrist from 2025 and upwards.