Vimsottari Dasa is peculiar to hindu astrology. This system sets the basic rules regarding which planet will exercise its influence at what time. A period of 120 years is taken as a full cycle of the planets in the following order :
Sun (6), Moon (10), Mars (7), Rahu (18), Jupiter (16), Saturn (19), Mercury (17), Ketu (7) and Venus (20). These planets rule over these years. This period of 120 years is called the Major Period
The planet governing at the time of birth is ascertained by the constellation of Moon at the time of birth.
Hindu astrology has not adopted Uranus, Neptune and Pluto in the system, as these planets were not known in ancient times. They give prominence to Rahu & Ketu which are the North Node & South Node respectively.