Genesia is an Earthlike Planet, independant of, but allied with Earth.
Until 2486, they were ruled by a collection of Kings and Warlords who were backed by a Warrior caste.
In 2486, a technical genius named Hieronymus Fox came to Genesia and in a three year campaign of public relations and commercialism, Fox the Genesians end-ran their former rulers and reformed themselves.
Fox reformed the warriors of Genesia into a Tennis league, where the matches were contested fiercely.
Over time, Fox modernized Genesia.
The history of Genesia is muddled. They were colonized by three seperate ships from Earth in the 1990s, but all accounts claim there were humans there before them.
Subsequent genetic studies indictate that there is a distinct human population on the world that does not come from Earth of the 1990s.
The Portal is in catacombs under Martinson City. The original Commonwealth city was buried in a flood and lay under a sedimentary layer.
Fox pursued archaeology about this, and his findings made no sense to anyone. Fox was describing the Commonwealth from the ancient city, but even he didn't know it. His descriptions are carefully neutral and fact based. He speculated about it in venues carefully separated from the forensics work.
Fox has discovered the Portal and was investigating it when he died in 2510. Genesia went into mourning and they've largely left his mad science alone, since they don't have many people who are capable of following Fox's thought process, let alone do anything constructive with it.
Genesians will listen to travelers and carefully note their stories. They know that the Draconian Empire would love to swoop in on them and everyone else, so their defenses are competent and professional.
But in their heart of hearts, they'll believe that Fox either invented or discovered the Fringepaths.