What four groups up aryan society list from top to bottom

Archaeological evidence indicates that civilization emerged in the Indus Valley around 3300 BCE. Over two millenniums, the inhabitants of this northwestern region of the Indian subcontinent developed into a prosperous civilization with a distinct cultural style. However, around 1500 BCE, a new culture, the Aryans, entered India through the Khyber Pass, and began integrating themselves into the social framework of the Indus Valley civilization. The origin of the Aryan people is subject to continuous scholarly debate; however, two theories prevail. Traditionally, it has been thought that the Aryans emerged in the Caucasus region and migrated westward into Europe and eastward into India. Another theory, the Cultural Diffusion Hypothesis, states that the Aryans originated in the Indus Valley. The Aryans furnished civilization in the Indian subcontinent with many impressive cultural and religious contributions and shaped Indian society for thousands of years with the creation of the caste system. Society According to traditional theories, the Indian caste system has its origins in the advent of the Aryans in the Indus Valley. Thus, this social stratification system was the product of the Aryan people’s will to separate themselves from, and subjugate, the local populations. Initially, this new society, which included Aryans and non-Aryans, was hierarchically divided into four varnas (i.e. castes). In fact, these four original varnas could be better categorized in two groups: Aryans and Non-Aryans. Nevertheless, the four varnas, from the top down, were: the Brahmins—Aryans (priests, scholars, and philosophers); the Kshatriyas—Aryans (rulers and warriors); the Vaishyas—Aryans (farmers, traders, merchants, and craftsmen); and the lowest caste, the Shudras—non-Aryans (laborers, peasants, and servants for the other castes). Each varna was divided into jatis (i.e. sub-castes), which identified the individual’s occupation and imposed marriage restrictions. Marriage was only possible between members of the same jati (or two that were very close). Both varnas and jatis determined a person’s purity level. Members of higher varnas or jatis had higher purity levels, and if contaminated (even by touch) by members of lower social groups, they would have to undergo extensive cleansing rites. 

Brahmins - Priests
Kshatriyas - Warriors, Kings, & Princes
Sudras - Dravidians
Vaisyas - Common People (everyone else)

Spanish conquistadors demanded labour from natives.