1) The export trade controlled by indian merchants was breaking down by 1850s.
2) European companie gained power,
They got concessions from local courts
& secured monopoly rights over trade.
3) local banks went bankrupt & the loans Which provided finance for trade by indian merchants were no longer available.
4) Therfore the old ports of Surat & Hoogly declined
& the new port of Bombay & Calcutta grew.