Agriculture, taking care of cows, and trade are the
responsibilities of Vaishy-s.
Service is the duty of Shudr-s.
Bhagavad Gitā, XVIII.44
The third category was Vaishy- s who were farmers, businessmen, and other trades people.
The financial welfare of the society depended on them. Shudra-s were assigned to serve above three groups because of qualities of their nature.
"There is no Védic scriptural sanction for any act of cruelty
or oppression or unfair discrimination based on anyone’s
birth. Birth-based discrimination and cruel treatment of
individuals and families which developed in Hindu society
over time as socially sanctioned practices are in gross
violation of ancient Hindu teachings and philosophy. Many
people that revere and owe allegiance to our ancient
Dhārmic teachings and philosophy have suffered over the
years as a result of such discriminatory practices. Such
suffering continues even today, despite the law of the land
and enlightened social and religious leaders having
continued to make, over the centuries, major and effective
contributions to diminish the depth and extent of these
discriminatory practices, which have nothing to do with
Hindu Dharma."
Swami Dayānand Saraswati
The fourth division was called Shudr- s. They did all the hard jobs requiring unskilled labor and some very unpleasant ones. They disposed off dead animals and removed garbage.
Gradually they became the untouchables because of the type of work they did and were dominated by other castes. Many reformers have tried to improve their lot and now it is illegal to discriminate on the basis of caste in India. One of the Presidents of independent India - highest position in the Government - was a Shudr.
Avarna
There is a fifth group of people who do not fit in with any of the four groups above and it is called - ‘ Avarna' - or Non-Divine. These people do not follow the Dharma or rules of the society. They are the lawless aggressors who kill, earn money by illegal means, cheat, give and take bribes, are drug dealers and sex traffickers.