offshoots of a ‘pure’ Rigvedic Aryan culture.
Changes in Later Vedic Period If the Rigvedic society was basically
tribal, then changes in this tribal structure are evident in the later Vedic texts.
The basis of this change was a gradual shift toward a different kind of
economy, with its emphasis on settled, plough agriculture. This is again
related to such factors as the colonisation of the fertile Ganges plains and
their extensions, and the newly acquired knowledge of iron, which enabled
agriculture to produce sufficient surplus. The later Vedic literature frequently
refers to iron, copper, tin, etc. and a variety of crops, which included wheat,
barley, millet, rice and pulses. The importance of agricultural operation is
revealed in some rituals, as also in the beginnings of sciences like astronomy,
which were directly linked with such operations.
    Linked with such changes were changes of great significance in the social
structure. The caste system, now with sharp distinctions between the four
varnas— brahmin, kshatriya, vaishya and sudra—took concrete shape in this
period. By making the vaishya and sudras subservient to the brahmins and
kshatriyas, the system provided the framework of social stratification in
India, although in later periods, the caste system acquired a much more
complicated structure.
    The decline of tribal identity was evident in the emergence of territories.
Even before the Buddhist list of sixteen mahajanapadas comes into
existence, we hear of the later Vedic janapadas such as Kuru, Panchala or
Videha. Related to the formation of territories was the formation of territorial
kingdoms, either monarchical or oligarchical, and also a change in the nature
of kingship, which brought in not only a series of elaborate sacrifices and
ceremonies—such as the asvamedha, vajapeya and ratnahavimshi—but also
gave sanction to the king as the appropriator of surplus in the form of regular
taxes. The priest, who in alliance with the king controlled the rituals and
ceremonies, appears to have met with resistance by the period of the Buddha.
Sacrificial rituals became more and more elaborate, even incongruous, in an
expanding agricultural and commercial economy.