Tradition

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

Lunisolar gathers ten calendars that solve the same problem the same way, keeping lunar months in step with the solar year by periodically inserting an extra month, and the group spans the length of Eurasia.

The Babylonian Calendar is the oldest of the ten and, transmitted with real later modification, close to the ancestor of the mechanism itself: alternating twenty nine and thirty day lunar months, intercalation eventually placed under mathematical prediction rather than direct observation of the new moon. Its logic passed into the Hebrew Calendar, which keeps that inheritance today, numbering months ecclesiastically from Nisan while opening its civil year in Tishrei. The Attic Festival Calendar of ancient Athens ran its own independent lunar months around the city's public festivals, one of many such calendars each Greek city state kept for itself rather than sharing one panhellenic scheme.

Three come from South and Inner Asia: the Hindu Panchanga divides each month into two lunar fortnights under several regional epoch systems; the Tibetan Calendar descends from the Kalachakra Tantra and fixes the Tibetan Buddhist liturgical round; and the Buddhist calendar of mainland Southeast Asia counts its era from the Buddha's parinibbana. Two carry an era rather than a wholly distinct mechanism: Vira Nirvana Samvat dates years from Mahavira's nirvana on the Panchanga's own structure, and the Saka era, carried into Southeast Asia, still opens the Balinese year with Nyepi. The Chinese Luni-Solar Calendar and the old Japanese calendar it shaped both track a sixty term stem and branch cycle beneath their months, the Japanese reckoning surviving mainly in Shinto festival custom layered over Japan's Gregorian civil year.