Orientalis - USRM
Orientalis, also known as the California Channel Islands or Mexico's Lost Archipelago, was claimed by the USRM on 10 December 2020.
Since it technically belongs to no country, they took it upon themselves to take care of it. It was not described in the treaty of Guadalupe, nor was it used by Mexico until further inspection of the treaty of Guadalupe ensued.
History of the Islands
Discovery
According to nps.gov , "The northern Channel Islands were home to many native Chumash communities who are believed to have inhabited the islands for thousands of years. When Europeans first reached the islands in the 16th century, they discovered a rich culture dependent upon the resources of the land and the sea for sustenance and survival."
The islands first became known to Europeans because of Spanish explorer Juan Rodríguez Cabrillo in 1542.
Modern Times
Not outlined in the treaty of Guadalupe-Hidalgo, the Channel Islands became in a geopolitical limbo. Both the Mexican and US governments exerted claims on the islands, despite neither actually having reason to claim them. The USRM claimed them in 2020.