1 language family
Oikoumeni is meant to be a parody. It is an alternate history, but it's not meant to be realistic so much as a mirror of the modern world. The question at the center of the project is: What if the Byzantine and its successors prospered into the colonial era, led the world in imperialism, and spread its influence across the globe? Linguistically, this means Greek essentially replaces Latin, and its many daughter languages are spoken throughout the Earth.
The alternate history uses as its turning point the era of Justinian and his successor Justin II. In the alternate history, Justinian successfully turns around the Byzantine Empire in the long-term, and his successors are able to maintain a far reach with a full treasury. The feud with the non-Chalcedonians subsides with the rise of Islam, which successfully brings about the demise of the Sassanians, a conquest of North Africa and India. The non-Chalcedonians, however, stave off the Muslim invaders and serve as a buffer for the Byzantine mainlands.