HN is not letting me edit, so here's the source: [ From the Museum Plaque / Card]. This is a photo I took when I was there.
https://raw.githubusercontent.com/theShiva/public-domain/mas...
The only thing incorrect in my original statement was, it was the province of Bengal (now the state?), not Calcutta.
Please read this entire thing. I've typed out the text in the photo verbatin. Last line says it all.
The Colonial Impact
Why did the British make Bengal their chief focus, and Calcutta their Capital? Bengal was India's wealthiest province, for her granary, rich in muslin, silk yarn, and salt petre, products which European trading companies were particularly interested in. Profits were high, and the East India Company saw it as a promising area to invest in.
They were proved right. By the mid-18th century, Bengal is playing a lead role in commerce., It provides the finances to sustain an expanding colonial state, especially after the Permanent Settlement of Bengal, revenue in 1793.
By 1856-7 Bengal alone is contributing 44% of the total revenue from British India. This is 260% more than Bombay. These figures tell us that Bengal is colonial India's most exploited region. Calcutta flourishes as a typical colonial city, linking the hinterland of primary production with plantations and mining resources, and exporting everything for the benefit of an imperial economy witch enriches Britain at Bengal's cost.