Samvatsara (संवत्सर) is a Sanskrit term for a "year" in Vedic literature such as the Rigveda and other ancient texts.
[3] A samvatsara is defined in Indian calendars as the time Brihaspati (Jupiter) takes to transit from one sign of the Hindu zodiac (i.e. rashi) to the next relative to its mean motion.
[3] The ancient text Surya Siddhanta calculates a samvatsara to be about 361 days, marginally short of a solar year.
[citation needed] The orbital periods of Jupiter and Saturn are approximately 12 and 30 solar years respectively.
"There is evidence to show that the cycle of Jupiter was in use in Southern India before Saka 828 (A.D. 905-6); but from that year, according to the Arya Siddhanta, or from Saka 831 (A.D. 908-9) according to the Sürya-Siddhanta, the expunction of the samvatsaras was altogether neglected, with the result that the 60-year cycle in the south became luni-solar from that year.