 Western Bolivia became one of the four Incan territories within its empire known as Qullasuyu, with an estimated one million inhabitants.The highest official of Qullasuyu ruled on behalf of the "Inca" (the emperor) and supervised a group of provincial governors, who in turn controlled the members of the Aymara nobility.Under a draft system called the Mit'a, the Incas forced the peoples under their domination to work in mines, on construction projects, or to serve in the armies.