The Vaisyas are the third-highest of the four varnas or categories into which Hindu society is traditionally divided, ranking above the Sudras. Vaisya includes a large number of distinct castes of similar ranking, traditionally traders, moneylenders, or farmers. They are entitled to wear a sacred thread. It is distinctly less common to encounter castes claiming Vaisya status in Sri Lanka and south India than in the north.
The category is certainly a very ancient one, for it is referred to in the Rig Veda (c. twelfth century B . C .). Vaisyas are clearly referred to in other early hymns as being Aryas, the Indo-European invaders, rather than Dasas, the Dravidian and other Aborigines of the subcontinent. According to the Zend Avesta, the Zoroastrian holy book, there was in ancient Persia a social category called "Vastrya," who ranked third in society below the Atharvas and Rethaesvas and bore a name that is cognate with the Sanskrit "Vaisya." The classical Indian lawgiver Manu (c. second century A . D .) spells out the duties of the Vaisya: "to keep herds of cattle, to bestow largesses, to sacrifice, to read the scripture, to carry on trade, to lend at interest, and to cultivate land." The economy depended on them, and the description of Manu still holds true
Hutton, John H. (1963). Caste In India. 4th ed. London: Oxford University Press.