Isidore was the first Christian chronicler to date all six ages

Evidence

True to his passion for ordering knowledge, Isidore, in his Chronica maiora (composed in 615 and reworked in 624), became the first Christian chronicler to calculate the lengths of each of the six ages, fusing sacred and profane historiography to produce the first Christian universal chronicle. — John V. Tolan, Saracens, 98

Categorization

• corroborated: 2 independent passages support this claim — John V. Tolan, Saracens, 98