The Hall of Armory, where the Trident of Atlan was created, was located in what would become the Kingdom of the Deserters. The Hall contained a mould where the Trident was forged from Poseidonian steel, as well as a structure that can play Atlantean messages as long as it was in contact with water.
Post-Sinking of Atlantis
Sometime after Atlantis sank under the sea, a number of Atlanteans broke off and formed the Kingdom of the Deserters, occupying an inland sea in Northern Africa. Eventually, however, the sea dried out and became the desert now known as the Sahara, ultimately causing its inhabitants to die. What remains of the kingdom is littered with debris and marine skeletons, and its once great underwater halls are now chasms located underneath the dunes.
In 2018, Arthur Curry and Princess Mera of Xebel traveled to the dead kingdom to search for the ancient technology located in the forge that would allow them to locate Atlan's Trident. They were able to reactivate the structure to play a message from King Atlan, which gave instructions for Atlantis' true heir to find the trident.