Indian historical tradition reckons the chronology from Svāyambhuva Manu to the Mahābhārata era in terms of the elapsed number of Manvantaras and Mahāyugas (Chaturyugas). It is recorded that six Manvantaras and the Dvāpara Yuga of the 28th Mahāyuga of the seventh Manvantara had elapsed during the Mahābhārata era.
Though the 5-year Yuga calendar continued to be in vogue starting from the early Vedic era to the Mahābhārata era, the duration of a Yuga and a Chaturyuga were increased from 5 years to 1200 years and from 20 years to 4800 years respectively at the end of the 28th Krita Yuga. Later, the duration of a Chaturyuga was again increased from 4800 years to 12000 years considering the differential duration of four Yugas in a ratio of 4:3:2:1.
During the pre-Mahābhārata era, ancient Indian astronomers further extended the duration of a Yuga from 1200 years to 432000 years (1200 times 360) and the duration of a Chaturyuga from 12000 years to 4320000 years (12000 times 360) with the objective of achieving accurate calandrical calculations. Unfortunately, those scholars who later updated the Purāṇas had erroneously deemed the increased calandrical duration of Chaturyugas as a given fact, and on that basis, narrated the chronological history of ancient India, resulting in, since antiquity, the loss of the true chronology from Manu to Mahabharata.
The research found that the epoch of the end of the 28th Krita Yuga of the Vaivasvata Manvantara would be the strongest basis, if it is accurately established, to retrieve that lost chronology. Lāṭadeva, a disciple of Āryabhaṭa provides verifiable astronomical details of the epoch of the Kritayugānta in his Sūrya Siddhānta. According to him, Mayāsura wrote Sūrya Siddhānta at the end of the 28th Krita Yuga when all five planets, the sun and the moon were in a perfect conjunction in Meṣa Rāśi (Aries) on Chaitra Śukla Pratipadā.This conjunction occurred on 22nd Feb, 6778 BCE.
ISBN : 978-8194321309 ; : 488 pages ; Aryabhata Publications; Paperback Version