India, which had been an important trading country since time immemorial was adversely affected by the restrictive policies pursued by the colonial government W.r.t commodity production, trade and tariff. As a result, India became an exporter of primary products and an importer of consumer goods. Britain maintained a monopoly control over India's imports and exports.
'Generation of a large export surplus' was the most important feature of India's foreign trade in the colonial era.
But the surplus came at a huge cost to the economy as it was used to meet the expenses on war and for the import of invisible items by the colonial government. All these led to the drain of Indian wealth, i.e., economic drain.