D100 Ancient Calendar Systems

Long before modern timekeeping, civilizations across realms — from mystic empires to otherworldly cultures — created their own unique ways of marking the passage of time. Some tracked the stars, others watched the growth of sacred plants or listened to the beat of the earth’s heart. These ancient calendars were more than systems of days and months — they were spiritual guides, political tools, and magical frameworks. Some determined when to plant crops, others dictated when rituals could be performed, or when dangerous gods would awaken. The calendars below are long-lost, half-remembered, or still in use by secret cults, strange planar beings, or secluded tribes. Use this D100 table to populate ancient tomes, hidden temples, scholarly debates, or time-related magic systems in your world. Nothing is fixed — roll once, twice, or as many times as you like to build unique cultures or prophecies. You are the keeper of time now.