There was a time in the Twentieth Century when the world was divided between two competing ideologies. For forty years, in a time known as the Cold War, the nations of the North Atlantic Treaty Organization faced the client states of the Soviet Union, with the ever-present threat of nuclear war hanging over both sides. The European continent was split in two, and the boundary that ran between the two rival alliances from the Arctic Ocean to the Mediterranean Sea was known as the Iron Curtain.
Five hundred years later, the ideologies that spawned the Cold War were lost in the depths of history. Mankind had spread out among the stars, and the United Worlds of the Solar System maintained the peace in humanity's home system. Across the depths of interstellar space, however, were the worlds of the Ophiuchius Group, centered on the 70 Ophiuchi star system. Settlers from Earth had reached the 70 Ophiuchi system, and found the remnants of an alien race. The Ophiuchians had died out millenia before, but scattered throughout the system were the technological relics of what was once a mighty interplanetary civilization. The settlers had discovered Ophiuchian science texts, and used them to decipher the aliens' language. Discovery after amazing discovery had been made, and the 70 Ophiuchi system had quickly grown in power.
By the Twenty-fifth Century, the people of the 70 Ophiuchi system had come to see themselves as the heirs of the lost alien race. They adopted the Ophiuchian language, and created an ideology that proclaimed them the next stage in human evolution. Across a distance of sixteen light years, the Ophiuchius Group and the United Worlds of the Solar System faced each other in an interstellar standoff. The people of the Twenty-fifth Century looked back into the past, and named the border between the two powers the Curtain of Space.