From the socio-anthropological perspective, the purok of the Iloko, otherwise known in Philippine history as baranggay, was an enlarged family. It appears to have formed for three main reasons: (1) filial devotion, (2) neighborliness, and (3) desire for protection.
The circumstances confronting the ancient Iloko settler could not permit any of these causes to be dissociated from the others. The cohesive force of blood and intestine relation of the Iloko, in a sense akin to the Malay tulang or bone relation, was largely the nourishment of filial devotion. Filial devotion, developed to flourish, slides into the neighborliness; and neighborliness nurtured, seeks to preserve itself from outside disturbances.