What problems did the incas overcome to rule their huge empire?

The land the Incans had settled on was hilly.  Due to hilly geographical nature of the mountain, farming and efficient movement was a real hassle. Incans were smart enough to device a road system that enabled them to overcome common geographic problems like distance. To make their mountainous lands for suitable for farming, they also built terraces with step-like platform where they could safely plant their crops.

affirmative action refers to the policies that take gender, race, or ethnicity into account in order to promote equal opportunity.

employers subject to title vii are prohibited from taking race or sex into account in any employment decisions. aa is a penalty for having any job group substantially statistically "underutilized" in any race or either sex. the employer must take steps to eliminate the underutilization, then stop, ending its aa efforts