Vimśottarī · the 120-year cycle

Vimśottarī is the daśā system the tradition reaches for first. It divides a full span of one hundred twenty years among the nine grahas, each holding a set number of years: Ketu seven, Venus twenty, Sun six, Moon ten, Mars seven, Rāhu eighteen, Jupiter sixteen, Saturn nineteen, Mercury seventeen. The order never changes, and the lengths never change.

Where a life enters the cycle is set by the Moon. The nakṣatra the Moon occupies at birth has a ruling planet, and that planet’s daśā is the one already running at the first breath, part-spent. From there the sequence proceeds in its fixed order, one graha handing to the next, for as long as the life lasts.

The Moon at birth decides where the clock is already turning.

One hundred twenty years is a frame, not a promise of lifespan; most lives touch only part of the cycle. Other daśā systems exist, keyed to different points in the chart, and the tradition keeps them rather than discarding them. Vimśottarī is the common default, not the only clock, and the codex names it as one system among several.