This is one of the many incarnations of what I know in my mind as the “Pas Taons.” This later became integrated to Mahhal lore as the site for the city of Derindonderak, but here it is still just the Pas Taons, and interestingly, I seem to have allowed some parallel-earth Spaniards to colonize the area (note the cities of Tripoli and Puerto Grande).
I suspect this is from when I was in high school. Maybe around 1982.