Why was the inca empire so successful

The Inca Empire was very powerful, good relationships with their neighbors.. The Inca leader Pachacuti  and his son Tupac Inca Yupanqui were the ones that expanded the Inca empire..They would work with their neighbors or people who would be of benefit to them by giving them gifts or favors and used the people as needed to advance. They had a great military organization and they were too powerful. Many people joined the empire   

Inca Yupanqui were the ones that expanded the Inca empire.

1. chiriquí a province that shares an indigenous culture with colombia. 2. san blas the largest population of indigenous people in panama. 3. bocas del toro in this province, the women make brightly-colored, embroidered blouses. 4. panama province home to three different groups of indigenous people in panama. 5. darien has less of an indigenous population than most other provinces in panama. 

What are our choice for it?