Variations in the climate of the Sahara region can, at the simplest level, be attributed to the changes in insolation because of slow shifts in Earth's orbital parameters. The parameters include the precession of the equinoxes, obliquity, and eccentricity as put forth by the Milankovitch theory.[2] The precession of the equinoxes is regarded as the most important orbital parameter in the formation of the "green Sahara" and "desert Sahara" cycle.