The Mayan kings timed their rituals with the stars and the Milky Way. They celebrated k’atun endings about every twenty years. At the end of each 20-year k’atun period, Maya rulers erected a stela (plural: stelae), called a stone tree, to commemorate the event.

On stone stelae, the Maya showed themselves in costumes with symbols associated with the World Tree. The headdresses on the stelae contained the Principal Bird Deity. In their arms, they held a “ceremonial bar” that represented the double-headed serpent of the ecliptic (the path the sun takes in a year). They chose these symbols because they wanted to connect to life (World Tree), the gods (Principal Bird Diety), and the sky (the ecliptic).

When the ending of a k’atun coincided with certain planetary positions, the Maya went to war.  They were careful observers of the sun, moon, and planets.

stela (stone tree) at Copan

 

(Adapted from source)