It is commonly said that Krishna departed the Earth in 3102 BC and the Mahabharata war occurred in 3138 BC, a little over five thousand years ago. But I just found indication these events may have happened much earlier. In this document, the Sri Vaishnava lecturer U. Ve. Velukkudi Krishnan Swami says this:
Dvaparayuga consists of 864000 years out of which 720000 years is the actual yuga and 72000 years of purva sandhi and 72000 years of uttara sandhi. Sri Krishna departed this material world on the last year of the actual yuga i.e. 720000th year. Mudal azhvargal were born after Sri Krishna during uttara sandhi kalam.... This confusion would arise if we assume that Krishna departed on last day of dvapara uttara sandhi. But in fact He departed on the last day of the actual dvapara yuga.
Let me explain what he's saying. There are four Yugas: Satya, Treta, Dwapara, and Kali. Now Dwapara Yuga and the Kali Yuga are often described as 864,000 years long and 432,000 years long respectively, but strictly speaking the actual Dwapara Yuga and actual Kali Yuga are 720,000 years long and 360,000 years long respectively. But each Yuga has two Sandhi Kalas or transition periods on either side, which are one tenth the size of their respective Yugas, as described in this chapter of the Vishnu Purana:
Thirty Muhúrttas constitute a day and night of mortals: thirty such days make a month, divided into two half-months: six months form an Ayana (the period of the sun's progress north or south of the ecliptic): and two Ayanas compose a year. The southern Ayana is a night, and the northern a day of the gods. Twelve thousand divine years, each composed of (three hundred and sixty) such days, constitute the period of the four Yugas, or ages. They are thus distributed: the Krita age has four thousand divine years; the Tretá three thousand; the Dwápara two thousand; and the Kali age one thousand: so those acquainted with antiquity have declared. The period that precedes a Yuga is called a Sandhyá, and it is of as many hundred years as there are thousands in the Yuga: and the period that follows a Yuga, termed the Sandhyánsa, is of similar duration.
So what Velukkudi Krishnan Swamy is saying is that Krishna departed the Earth on the last day of the actual Dwapara Yuga. We, on the other hand, are living five thousand years after the start of the actual Kali Yuga. So that would mean that between Krishna departing the Earth and our time is the 72,000-year Uttara Sandhi period of Dwapara Yuga, plus the 36,000-year Purva Sandhi period of the Kali Yuga, plus the 5,000-odd years that have elapsed in the actual Kali Yuga thus far. So that would imply that Krishna departed the Earth 113,000 years ago, not 5,000 years ago as is commonly believed.
My question is, do any scriptures describe when exactly Krishna departed the Earth in relation to the Uttara Sandhi period of the Dwapara Yuga and the Purva Sandhi period of the Kali Yuga? Did he depart the Earth at the end of the actual Dwapara Yuga, or at the end of the Uttara Sandhi period of the Dwapara Yuga, or the end of the Purva Sandhi period of the Kali Yuga, or what?
