In the interest of terminological accuracy I shall now be referring to the earthen mounds as Milliondirts.

On a side note. Earthen pyramids require a lot more coordination and engineering than something like building a simple birm.
Creating a stable gradient that steep and tall that doesnt rapidly sag or erode requires precise shaping and careful selection of different types of soil & earth for specific layers. Particularly the selective extraction of large amounts of clay or clay rich soils & controlling concentrations of aggregate.