It's not necessary to know all of the place names in Isaiah 20 and where they are on a map, although like the last pieces of a finished puzzle, it certainly makes the picture more clear that Isaiah is describing. What is most important to know about Isaiah 20 is that God is infinitely stronger than any of the kingdoms of the earth. Isaiah 20 illustrates an example of this by showing the historical sweep of the king of Assyria and his armies hundreds of miles from the north down toward Jerusalem where, after having made a systematic progress of destruction for most of that distance, he is stopped in his tracks just short of Jerusalem.
Politics is seldom simple. But the truth usually is.