Pachacuti asked other states to join him. States that did not join were destroyed by his army. States that decided to join needed to send the children of their respective rulers to be educated by the Inca in Cuzco. After the children were raised into perfect Inca subjects, they .

They were indoctrinated

Explanation:

After the children of the have been taught(Educated)  about their (Inca) administration systems, then allowed them to return and rule their native lands. This allowed the Inca to indoctrinate the former ruler's children into the Inca nobility. They even allowed them to marry their daughters.  

were returned home to rule their native lands.

Explanation: Pachacuti who happens to be the 9th spa of Inca in the Cuzco empire frequently sends spices to areas he would love to include in his empire to learn about how rich they were, how organised their Political structures were as well as the strength of their military. After getting this informations, he would often send them gift and tell them he would like it if they joined his empire, promising to enrich them, often times many joins his empire but in regions where they refused to join, their leaders were killed and their children taken to Cuzco where they will be taught by the Incas about their adminstration and political systems after which they will be returned back to their native lands to rule. The inca uses assimilation techniques amongst others to conquer regions, they indoctrinate these young rulers into Inca nobillties before sending them back to their native lands to rule by what they were taught.