Ancient Baklunish is one of the ancestors of Common, though little resemblance remains between the two in the present day. It is the language of all official and religious documents west of the Yatil Mountains.
Ancient Suloise is an ancient and widespread language that became almost extinct after the destruction of the Suel Imperium. It is rarely used in modern time aside from the Scarlet Brotherhood and a few isolated scholars.
Flan is probably the oldest language spoken to any notable extent, although dialects vary considerably through the Flanaess. A stagnant language, it is difficult to translate modern concepts (such as magic) into Flan.
Low Baklunish is descended from Ancient Baklunish but much has changed by time. Low Baklunish encompasses the contemporary, colloquial Baklunish dialects.
Old Oeridian was completely free of outside influences until the Great Migrations. Its grammar is thus unique and it is almost impossible to translate it into any language other than Common. Many of the books, records, and holy texts of the Aerdi were written in Old Oeridian.
Ur-Flan was an ancient language used by the Ur-Flannae people thousands of years ago in the Flanaess. It died along with the Ur-Flan empire and is never spoken aside from by a tiny number of scholars. Some fragmentary writings survive. Unsurprisingly, Flan is closely related.