While they did not all rise to the equal amount of power and influence at the same time, they did organize and participate in an international system of diplomacy, trade, and culture.
[1] States interacted through letters, written in Akkadian, the international language of diplomacy, and through oral messages.
Thus it was important for him to gain said legitimacy, which efforts resulted in the Egyptian–Hittite peace treaty, where Egypt de-facto recognized his rule.
King Akhenaten moved the capital of Egypt to Amarna and there kept the correspondence of him and his father with the rest of the members of the Club of Great Powers.
They were the kings of Babylonia, Assyria, Mittani, Hatti, Alashiya (on Cyprus), and Arzawa (in south-west Anatolia).