The Navajo population

I looked on the Navajo nations' website and under history it states that the population is over 250,000 people. In the book it states that there are 300,000 which is closer to the number found in the 2010 U.S. Census, which stated that,"There were a total of 332,129 individuals living in the U.S. who claimed to have Navajo ancestry." This information was found in the Navajo Population Profile: http://www.nec.navajo-nsn.gov/Portals/0/Reports/NN2010PopulationProfile.pdf
The Navajo Nations' website is: http://www.navajo-nsn.gov/