Old Republic Earth is a version of the planet Earth, a parallel-universe version of the Universe of the Magisterium except that the Official Magisterium never emerged on Old Republic Earth independently, and that there is a unified North American Republic instead of hundreds of North American city-states. Weapons of mass destruction (nuclear, biological, and chemical) are still outlawed here by common consensus of governments and religious leaders. The Sino-Russian Socialist Empire, Stygia, the Southern African Republic, the Old Republic, the Mexican and Brazilian Empires, the Oceania Free State, the Islamo-Indian Caliphate, and the Astra-Asian Unity all still exist here like they do in the Universe of the Magisterium.
Two religious movements have taken the place of the Official Magisterium on Old Republic Earth: the Islamo-Christian Church, a fusion of Christianity and Muslim beliefs; and the Neo-Pagan Church, which worships a polytheistic pantheon including Jesus Christ, Buddha, and deities of the Hindu, Shinto, Greco-Roman, and Norse religions. Islamo-Christianity is the majority religion worldwide, but Neo-Paganism is fairly strong in Asia and parts of Africa.
Transdimensional Void Runners who have visited Old Republic Earth hail from the Universe of the Magisterium (mostly Hesychast Order monks and nuns) and the Earth of His Dark Materials (see His Dark Materials in TVR).
Space travel and off-Earth colonization is largely resembles that in the Universe of the Magisterium, and Old Republic Earth has it's own version of the Astrotech Futurist Cartel.