The Moon Mahadasha is the period of Chandra in the Vimshottari dasha, lasting ten years. In the fixed sequence it follows the Sun and precedes Mars. As the significator of the mind, the emotions, the mother, and the public, the Moon in its dasha is traditionally read as a time when feeling, domestic life, the relationship with the mother, and one's public standing become prominent, the results shaped by the Moon's condition, waxing or waning, well or ill placed, in the birth chart. The dasha sequence a person enters at birth is fixed by the nakshatra of the natal Moon itself. These are the interpretive conventions of the tradition; the Vimshottari system is a timing method that assigns each of the nine grahas a period of set length in a set order across the hundred-and-twenty-year cycle.
Because the whole Vimshottari calculation is keyed to the Moon's nakshatra, it depends on a sidereal zodiac and therefore on an ayanamsha, the measured offset between the sidereal and tropical zero points produced by the precession of the equinoxes. Different ayanamsha values, Lahiri, Raman, and Krishnamurti among the most used, shift nakshatra boundaries by a degree or so relative to one another, and a birth Moon lying close to a nakshatra boundary can fall under a different dasha lord, and begin the Vimshottari sequence at a different mahadasha, depending on which ayanamsha the astrologer has chosen. This is one of the more consequential places where a seemingly small technical choice, invisible in the finished chart, can change the entire timeline of predicted periods that follows from it.