The correct answer to this open question is the following.
I would hypothesize to create a United Nations "UN" type of meeting between the following three civilizations: the Sumerians, the Harappans, and the Ancient Egyptians. With imagining that these three civilizations existed at the same time, the peace treaty that I would create would allow each civilization to exist and retain its identity and equality.
The meeting would be in the oldest city on planet earth, Eridu, in the heart of Sumeria, in what today is the region of Iraq. There, my organization that is called Ancient Civilizations for Peace (ACP), would meet to discuss the terms for a new treaty of peace and prosperity between nations.
The important elements to be discussed by the Sumerians, Harappans, and Egyptian delegates would be the definition of territorial boundaries, immigration, the responsible use of water from the four main rivers(Tigris, Euphrates, Nile, and Yellow River), trade, and foreign policy.
The Treaty will be called the "Treaty of Three" (TT) because it encompasses the interest of the three civilizations.
