estuvieron armando
-they/you were assembling
Preterite progressive ellos/ellas/ustedes conjugation of armar.

armar

Este es el objetivo que los conspiradores de la oscuridad estuvieron armando en los primeros años del siglo 21.
This is the goal that the dark cabalists were setting up in the first few years of the 21st century.
Word of the Day
Christmas carol