Thus, many puranas are there which describes cycles within cycles,well cycle could be understand as units of deva years, each of which equals 360 human years.The following description starts with the smaller cycles and works up to the larger ones. The length of each cycle is given in ordinary human (earth) years, as well other units where appropriate. Large numbers are described using the conventions of American English: thus, a million is a thousand thousand, a billion is a thousand million, a trillion is a thousand billion.
This description is based on numerous sources, which are given in the "References" section at the end of this document.
