A literal kingdom on earth
Most people don't understand that the Kingdom of God is a literal kingdom, a government both divine and royal ruling over literal people on the earth. This is not merely a symbolic or a spiritual rule, a sentiment that exists only in human hearts. As we will see, it is far more. And Jesus simply continued the prophecies about this Kingdom that had begun to be revealed in the Old Testament.
A prophecy of this coming Kingdom is graphically depicted in Daniel 2. In this prophecy the Babylonian king, Nebuchadnezzar, was shown an image that represents the major kingdoms or empires that would dominate the Middle East. The image represents first the kingdom of Babylon, and then three successive kingdoms that would rule until the Kingdom of God would be "set up." This Kingdom of God will put an end to the rule of the previous kingdoms.