From Our World To Theirs  Stela: The "Stone Tree"  The Maya
carved hieroglyphs on large stone monuments called stela, or
"stone tree". These carvings frequently recorded important
historical events in the lives of Maya rulers.  The Maya
celebrated k'atun endings approximately every twenty years. At
the end of the 20-year k'atun period, Maya rulers erected a
stela to commemorate the event. They depicted themselves at the
time of these ceremonies.  Stela at Copan