Daniel 2 and Daniel 7 are parallel passages, both teaching about the world empires that precede the world empire of the Lord Jesus Christ.  Focusing upon Daniel 2, Nebuchadnezzar's image had a gold, silver, brass, iron, and part of iron and part of clay sections.  The gold represents Babylon, the silver Media-Persia, the brass Greece, and the iron Rome.  And, Rome has a phase or part to it - ten toes, which represents 10 coming kings, and in the days of these ten kings God is going to set up a kingdom that will never be destroyed - that is, the kingdom of Jesus Christ.