In the mid-first millenium Aryan settlements began to move east toward the Middle and
Eastern Gangetic Valley. There was a climactic shift which caused the Punjab and the Western
Gangetic Valley to become more arid. Thus the basis for agriculture became less secure at the
same time as the jungles blocking the Aryan path became more penetrable. There may also have
been the desire among some groups to escape the monarchical form of political organization.
After this shift east, between 600 and 400 b.c., we come to the emergence of the state form of
organization. In this period of growing urbanization and trade, Aryan society came into contact
with more of the subcontinent, thus one say that the history of the subcontinent really came into
being.
In the Middle and Eastern Gangetic Valley the migrating Aryans found dense forests and
marshland. Archeological evidence shows that the indigenous peoples there had been growing
rice from the sixth millenium; however, they had used a scattering method which could just
support subsistence. There were not the methods and technology for intense rice cultivation. For