This paper presents linguistic and philological analyses of glossed medieval Georgian transcriptions of the Middle Mongol zodiac terms in the fourteenth-century anonymous ასწლოვანი მატიანე Asc'lovani Mat'iane (Chronicle of One Hundred Years), revealing unique details on Middle Mongol as attested in medieval Georgia. This is the first instalment of the authors’ joint research on this vastly important, largely untapped contemporaneous Georgian source on medieval Mongol language, culture and history.