the commodities in circulation being largely items of basic consumption.
Some, such as metals and salt, would then enter into the larger circuits of
trade which linked the nagaras with each other, a qualitatively different trade
from the local circuits and where commerce was handled by the gahapatis
and later, by the setthis. This trade required investments of large amounts and
close contact among the traders. Some of these contacts went back to earlier
links between political centres and, with the growth of commerce, took on the
character of commercial links. The major routes (outside the local circuit)
also linked the political centres. These links may originally have been forged
through marriage alliances. With the growth of trade, some of the political
centres acquired commercial importance as well. Thus Taxila in Gandhara
retained its commercial importance since it had access to west Asia,
particularly after the sixth century BC, when it lay on the eastern edge of the
Achaemenid empire.
                           SIX MAHANAGARAS
  The six mahanagaras mentioned in Buddhist sources were:
  Sravasti (the capital of Kosala in the Buddhist period) seems to have
  replaced the Ayodhya of the Ramayana, possibly because the latter was
  too far south and therefore, not on the main route running closer to the
  Saketa remains a major city on the route from Kosala to Kausambi,
  thereby giving Kosala the advantage of two major cities;
  Rajagrha, the capital of Magadha, commanding the fertile tract between
  the Ganga and the eastern outcrops of the plateau;
  Champa, the capital of Anga (the Bhagalpur region of Bihar) and an active
  river port on the Ganga controlling trade going east;
  Kasi, the centre of the kingdom of the same name and close to the
  confluence of the Ganga and the Gomati;
  Kausambi, near the confluence of the Ganga and the Yamuna, with access
  to the route southwards through the Vindhyas.
Trade Routes