The smallest societal groupings were families and clans, consisting of individuals sharing a common ancestry, language, culture and customs. As the groupings expanded in size, they incorporated extended families and close neighbors, again sharing customs, language and experience. As these distinct small groups shared a local geographic area with other groups, inevitably interaction occurred, sometimes through rivalry or battle, frequently through intermarriage, and many times through mutual defense, there grew up a commonality of culture, language and custom in an expanded area among various small groups, which provided a foundation for the development of political and economic unities to naturally evolve. These groups found they had a common self-interest, in addition to their shared language and cultural backgrounds, in finding ways to join together. At the same time, the proximity also tended in many instances to accentuate small differences among those with a common general background.
Sri Aurobindo observes: “Thus Greece, Italy, Gaul, Egypt, China, Medo-Persia, India, Arabia, Israel, all began with a loose cultural and geographical aggregation which made them separate and distinct culture-units before they could become nation-units. Within that loose unity the tribe, clan or city or regional states formed in the vague mass so many points of distinct, vigorous and compact unity which felt indeed more and more powerfully the divergence and opposition of their larger cultural oneness to the outside world but could feel also and often much more nearly and acutely their own divergences, contrasts and oppositions. Where this sense of local distinctness was most acute, there the problem of national unification was necessarily more difficult and its solution, when made, tended to be more illusory.”
Sri Aurobindo, The Ideal of Human Unity, Part One, Chapter 12, The Ancient Cycle of Prenational Empire-Building–The Modern Cycle of Nation-Building, pg. 94