I thought you were asking what comes after 23 );
The answer is a political system
<h2>Answer: The Gulf of Mexico
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The Gulf of Mexico is an ocean basin that formed after the collision of the continental plates and the sinking of the seabed during the rupture of the former Pangea mega continent millions of years ago.
This gulf is also the ninth largest water surface in the world, which is contained among the littorals of Mexico, the United States and the island of Cuba. Therefore, this mass of water corresponds to the Atlantic Ocean in the northern part of the American Continent.
The main reason for the wall's construction had always been defense. Since China's first dynasty, the empire faced a near-constant threat of attack from the nomadic tribes to the north. This included those famed Mongols as well as lesser-known groups like the Xiongnu and the Göktürks.