In Daniel 7, the four great beasts symbolize empires. The Babylonian empire, the Persian empire, the Greek empire and the roman empire. These happened in succession just as Daniel said. But the fourth and final empire represented by the fourth beast with the ten horns is pictured on a stage where it is ruled over by ten kings, ten individuals. That is in place whenever Jesus returns. We know historically, this has never been in place so since everything else in that prophecy was all literally fulfilled, we believe that has to be literally fulfilled as well. That has been the basis for what a lot of theologians have called a reuniting or a revived roman empire. The old Roman Empire was a lot of Europe, the western part of Asia, the northern part of Africa - we don't know what the exact nations are but it does tell us there will be a reviving of the Roman Empire under 10 rulers. This is just one more prophecy that provides signs of Jesus return.