We know but little of the history of the Indian subcontinent. That also holds good for the 5th and 4th centuries BC. There are only a few radiocarbon dates, and written sources display little interest in exact chronology. Consequently, we are forced to stick to the broad outlines of the story. Linguistic evidence and archaeology combine to show the continuing acculturation taking place between the Indo-Aryan groups and the autochthonous inhabitants. In the north, Indo-Aryan languages came to predominate, but when one looks at culture at large, old and new elements can be seen to fuse into a new synthesis. In the south, comparable events occurred, but the local Dravidian languages stood up to the Indo-Aryan languages better. The acculturation process also took in influences from outside the subcontinent, because there was frequent interaction with Iran—from the 6th century BC onward more specifically the Persian Empire—with Central Asia by way of the northwest, and with Southeast Asia, especially Burma, by way of the northeast.
Acculturation resulted in an Indian subcontinent that culturally speaking was relatively homogeneous: the many contacts over land and especially along the coasts brought about cultural unification. One of the instruments of this unification was Brahmanic religion, named after the priests, the Brahmans. The Indo-Aryans had brought this religion with them, and in India it subsequently developed into what later was to be known as Hinduism. Cultural unification, however, did not imply any form of political unity. Along the Ganges, a number of states developed in a long-drawn out process, but none of these managed to overcome their neighbors. Not until the late 4th century BC did a hegemonic state arise, when the so-called Maurya dynasty began building an empire.
It is suspected that the dynamics of contact between Indo-Aryan and Dravidian groups has also played a part in the growth of the caste system, a phenomenon about whose early history nothing is known with certainty. The Indo-Aryans divided their society into three layers: the priests, the brahmana; the warriors, the kshatriya; and the farmers, the vaishya. Whether these were hereditary, endogamous groups, as were the later castes, is not clear. It appears that after the Indo-Aryans settled in the Indian subcontinent, a fourth category was added: the dasa, the conquered, later also known as the shudra, the servants. This fourth group included those members of the autochthonous inhabitants who were seen as a part, an inferior part but a part all the same, of Indo-Aryan society. Autochthonous people, however, who were not or but little influenced by Indo-Aryan culture were considered to be outside the pale of society altogether. These four layers, the so-called varna, were further subdivided into a complicated system of social hierarchies, with everybody finding a place in one of the numerous jata, a concept that much later (by the Portuguese) was translated as “caste.”
Culturally, the 5th and 4th centuries were important for India. In this “classic period,” the cities along the Ganges were the most important centers, but other parts of the subcontinent shared, more or less, in the cultural dynamics. By the end of the 6th century and early 5th century BC, iron had come into use all over the subcontinent, and cities, trade, and irrigation agriculture were flourishing. Indicative of the growth of interregional exchange is the introduction, in the 5th or 4th century BC, of silver and copper coinage, based on Persian coins that circulated in the northwest (present-day Pakistan). Alphabets were derived, in the same period, from Aramaic examples, again under Persian influence. Alphabetic writing helped intellectual life to expand. Exegesis of Brahmanic writings, especially the Vedas, gave rise to a range of specialist scholarship: astronomy, geometry, and most importantly, an advanced linguistics.
This period of socioeconomic and cultural change was also a period of religious ferment: several religious movements and sects began competing with orthodox Brahmanism. Brahmanism was a ritualistic religion: honoring the gods involved extensive rituals, especially sacrificial ones. The holy texts, including the aforementioned Vedas, the most ancient ones, provided the rules for these rituals. Wandering preachers now threw doubt on Vedic learning and advocated, among other things, an asceticism that went back to pre-Vedic, probably pre-Indo-Aryan patterns of thought. Of these new movements, Buddhism would turn out to be the most important.
There is no agreement about when the founder of Buddhism, the Buddha (“Enlightened”) Siddhartha Gautama, lived, but nowadays many scholars accept the period 480-400 BC as reasonable. Central in the teachings of Siddhartha Gautama and his followers are “the four truths”: our earthly life is miserable; the cause of this misery is desire; we can end misery by banishing all desire; in order to banish desire, we should follow the “eightfold path,” which comprises a set of rules for right living. Buddhism denies the necessity for any ritual and worship, and teaches that one can escape the supposed cycle of rebirth by one’s own efforts. It was acknowledged that not everybody would be able to follow the eightfold path, and thus the distinction between monastics and laymen came into being. Buddhism was also a missionary religion, and in the centuries to come would spread across large parts of Asia.