Each yugam has SANDHAI prior to start and SANDHYAMSAM after the yugam. Period of this is different for different yugams. For Kaliyugam SANDHAI and SANDHYANSAM is 100 divine years (36000 human years) each. There is PRALAYA after each yugam. Sandhyamsam may be the closure priod of a yugam and SANDHAI is the start-up phase of the yugam. After each Manvantara there is a SANDHI equivalent of 4800 divine years (4800*360 human years). Next manu is created by Brahma during this period. What remains after each pralaya when the entire world is submerged in water and what gets created afresh and what happens after each manvantara and kalpa is not known. Our scientific knowledge is limited as we saw in the recent prediction of Tsunami after an earthquake which never took place... post mortem of this people give a different theory to say why Tsunami did not occur this time. Kirankumar