The 1921--1924 hyperinflation happened mainly because of three things: the ongoing internal political instability in the country, the occupation of the Ruhr district by foreign troops, and when the Weimar (modern-day Germany) government printed too much banknotes to pay reparations after the 1923 French invasion. Because the banknotes were not matched by Germany's production, their value fell.
COULD USE SOME END-OF-THE-MONTH DONATIONS! THANKS!