Not changing my proposals
El Río Rojo: Cutting through the sandy shrubland of the western portion of the region is El Río Rojo (The Red River) which in centuries past provided irrigation for more traditional farmland in the area and in the present feeds a vast brick industry from its red clay deposits that give it its name. Besides its main course the relative flatness of much of the area around it gives a rather unique obstacle for travelers and those that which to settle in the region. During the rainy season where the river is full it forms hundreds of tiny tributaries that turn the land around it into clay marshes for miles while in the dry season the sun bakes it into concrete like terrain nearly impossible to dig through. Beyond even this to the west is a great mountain range that makes up part of the greater coverage of mountains around the region preventing rain from falling in great amounts making much of our basin into a sparse sandy shrubland.
The Walls of Nikase: During the conquests of Queen Nikase of Heliopolis to forge her Empire of the Sun she found herself in a land, our land (us and the other team ofc) ripe for conquest being displaced and half destroyed by wars waged apparently against ourselves. It was only a few weeks of campaigning in our land did she learn the truth. The Anakemites, great towering giants ranging from as tall as a stout oak to many dozen meters tall that came from over the mountains to feast upon the land each generation. Nikase and her hoplites barely managed to survive the feasting season of the Anakemites, though with their bellies full on the flesh of man they once more retreated beyond the mountains to their homeland. Scarred from the battle and understanding the threat to her nascent empire the Anakemites presented she gathered forth her regiments and marched the grandest army the world had ever seen beyond the mountains. They barely survived, fifty thousand soldiers clad in bronze went over the mountains and barely ten thousand returned from the slaughter.
The kingdoms of the Anakemites were beyond the martial prowess of Nikase and the strength of her regiments of hoplites. There was no chance to conquer them, so Nikase sought to at least secure her realm from the hornets nest she had now kicked. The Nikase mountains, that she named after herself, that the Anakemites crossed over to feast had great bodies of water on either side of them, today known to be inland seas, could be fortified to withstand their assault. So she gathered the great architects of her Empire to design a palisade worthy of repelling the titanic foe, and she gathered the tribes of the region, our ancestors included, to build it. Promising the land to forever be in our ownership under her fealty if we built the wall and garrisoned it. We agreed, a generation of construction went forward as the walls were built higher and higher each year to withstand the enemies beyond them.
Nikase and her Empire are long gone and modern archaeology shows that while a kingdom beyond the mountains did exist they were of rather average size and more likely simply raided the people of the region and the fabled Great Wall being unnaturally large Basalt Columns that show signs of being built on by the natives of the region with the building of the wall and the giants it was meant to repel being nothing more than myth. [Location, SouthWest/West/NorthWest portions of the map being a small mountain range with the unique addition of giant basalt columns that form natural walls in the valleys and passes between the mountains.]