When the Portuguese began to trade extensively with South Asia, they quickly noticed a fundamental difference between South Asian societies and those of other world areas. In India and Sri Lanka, societies are broken up into a large number of groups who do not intermarry, who are ranked in relation to each other, and whose interactions are governed by a multitude of ritualized behaviors. The Portuguese called these groups casta, from which the English term caste is derived. In South Asia, they are described by the term jati, or birth. According to traditional culture, every person is born into a particular group that defines his or her unchangeable position within society. Caste System in Ceylon (The dominant caste among the Sinhalese population is the Goyigama. Although the government keeps no official statistics on caste, it appears that the Goyigama comprise at least half the Sinhalese population) Durava Cast ( The Durava community can boast of a long presence in Sri Lanka which may date back to several centuries or even millennia if their claims to Naga ancestry are to be taken seriously. Yet this largely coastal population has had to struggle hard to debunk a myth perpetuated since Portuguese times that they are toddy tappers, one which they believe lowers them in the eyes of other men.) Karava Cast ( The history recorded here charts the Karava from the time of the 'Mahabharata', to their arrival here during the Kotte period, their rise and fall through the Portuguese, Dutch and British periods, and the sweeping social changes of the 20th century. ) Tamil Castes