"Utsarpiṇī" is a period of progressive prosperity and happiness where the time spans and ages are at an increasing scale, while "Avsarpiṇī" is a period of increasing sorrow and immorality with decline in timespans of the epochs.Each of this half time cycle consisting of innumerable period of time (measured in "sagaropama" and "palyopama" years) is further sub-divided into six "aras" or epochs of unequal periods.