The aim of this article is to recognize and compare some of the demographic characteristics of Iranian and Indian tribes, who along with their traditions have preserved their social order. One of three types of society in the world is tribal society that Iran and India are availing it. The definition of the tribal system is different in various parts of the world. The tribal system in Iran is based on animal husbandry and growing agricultural means in a limited area and such a society is often migrant. While in social tribal system of India, some groups are relatives and make their living by farming in a wide scope of land, and animal husbandry in a limited area and they are completely settled. Today, the population census of India shows the increase in the tribal population. On the other hand, the population census of Iran shows the decrease in tribal population despite of its relatively high birth rates. One of the basic causes of this decrease in the population of tribes in Iran is its definition who have merely considered the migrating tribes, but never paid attention to those who have settled. It should be known that such a difference in definition caused that population of tribes in India has been increasing while in Iran has been decreasing.