Vimshottari is the period system in general use, but it is not the only one the Sanskrit literature contains. Ashtottari runs to a hundred and eight years, Yogini to thirty six, and there are schemes tied to the sign rather than to the lunar mansion, along with a Kalachakra dasha that takes its divisions from a different geometry again. Classical texts discuss which system suits which chart, and the question is a live one in the commentarial literature rather than a settled matter.
The Brihat Parashara Hora Shastra, the large compendium attributed to the sage Parashara, is the text most often cited for Vimshottari and sets out the sequence and the subdivisions. The date and composition history of the work as it is printed today are debated, and the atlas records that rather than assigning it an age it cannot support.
David Pingree's survey of the Sanskrit astral literature is the standard guide to how this body of writing is organised and how it developed, including the substantial layer that entered from Greek astrology in the early centuries of the common era. The period systems are not part of that borrowed layer. Whatever their origin, they are among the features that make the Indian tradition's handling of time distinct from the Hellenistic material it otherwise absorbed so thoroughly.