12 rounds of 5 years (60 years) make one yuga in Jupiter cycle.
Each of the 5 years is known as a Yuga of Jupiter and 12 Yugas of Jupiter make 60 years named after Prabhava, Vibhava etc., but starting from Vijaya.
Thus we find two types of time-reckoning in the Vedic society in those days - one, solar year based Siddhantic time which incorporate Chatur Maha Yugas counted for a day of Brahma (Kalpa) and another, the Jupiter Yuga of 60 years whose basic unit is 5 year Yuga for religious austerities.
Today this system of 60 years is used for solar years. In absence of adherence to Vedic way of life we have given up 5 year Yuga of Jupiter cycle, but use the year names of the Jupiter cycle. We continue to use the two in any religious activity. We start from Siddhantic Kalpa and continue with the year name and Ayana (of 5 year Yuga) and the subsequent smaller divisions of time.
Even the Siddhantic Yuga is a twin. One may recall the sankalpa mantra stating 'Kali yuge Pratame Paade' which refers to the 1st paada of Kali yuga (called Utsarpini) which is the 1st half of Kali Yuga. So there are two padas in Kali Yuga. It must have been so for the other Yugas too (Krita, Treta and Dwapara)
The basic unit of Time is a day. And a day has a day time and an opposite of it, namely night time.
By the 13th day of the Exile period, Bheema told Yudhisthira that 13 days are equal to 13 years for one who is steadfast in his observance of vows of the Vedic life. Since Yudhishthira was leading such life he can be said to have completed 13 years.
Mahabharata, Vana parva – section 52
Mahabharata - 3-49
ahorātraṃ mahārāja tulyaṃ saṃvatsareṇa hi
22 tathaiva veda vacanaṃ śrūyate nityadā vibho
saṃvatsaro mahārāja pūrṇo bhavati kṛcchrataḥ
23 yadi vedāḥ pramāṇaṃ te divasād ūrdhvam acyuta
trayodaśa samāḥ kālo jñāyatāṃ pariniṣṭhitaḥ )
Rama was not alone in terms of 1000s of years of life, even the Pandyan King "Maakeerthi" (who presided over the Assembly where Tol Kappiayam was inaugurated) was praised as having ruled the kingdom for 24,000 years which means he was on throne for 66 to 67 years.
Rama's father Dasaratha was said to have lived for 60,000 years. This is just beyond any calculation, but this was told to express his old age. Rama was a late child and Dasaratha was very much older when Rama was ready for throne. A phenomenal number of age was given to Dasaratha to drive home the point that he was already old. If such age is to be taken in face value, then his wives also must have lived for tens of thousands of years, but nowhere it is told so.
Similarly all the three brothers of Rama were born around the same time and left the world around the same time. If it is true that Rama lived for 11,000 years then his brothers also must have lived for so long. But that is not being told anywhere.
"raamo raajyam upaasitvaa " - Rama rajyam for 11,000 years.
What does this mean?
" dasha varSa sahasraaNi dasha varSa shataani ca |
raamo raajyam upaasitvaa brahma lokam prayaasyati || " (1-1-97)
97. dasha+varSa+sahasraaNi= ten, years, thousand; dasa+varsha+sataani+ca= ten, years, hundred, also; raamaH= Rama; raajyam+upaasitvaa= kingdom, on reverencing; brahma+ lokam+gamishhyati= Brahma's abode, voyages.
"On reverencing the kingdom for ten thousand years plus another one thousand years, [i.e. for a total of eleven thousand years,] Rama voyages to the abode of Brahma... [1-1-97]
Comment: In rama raajyam upaasitvaa... the word used is upaasana is not ruling by sceptre but 'reverentially idolised the kingdom...' as one would regard or treat his personal god with reverence. Rama thus reverenced his kingdom as a devotee of his subjects and this is the concept of raama raajya.
The commentary above puts the entire issue in a different perspective!!
Raama established Raama rajyam for 10,000 + 1000 years after which He left for His Abode.
It is often told that Raama's story will live as long as Himalayas and the Ganga will live. Rama Rajyam or Rama's memory will be there till Ganga flows. Perhaps Ganga will flow for 11,000 years after Rama's birth!! Today scientists accept that Ganga will vanish one day. We find reference to this in other olden texts too.
Did Valmiki compose Uttara Ramayana?