After the wealthiest dynasty in history ‒ the Mughal dynasty ‒ had died out, in the mid-19th century there were many contenders to replace it as the rulers of India. In addition to their own (Marathas, Wodeyars, Sikhs), European powers also claimed the golden throne. And most of all I wanted to decorate my crown with the 'eastern pearl' of the British Empire.
The first path to the Indian lands was trodden by English merchants. Back in 1600, the 'Company of Merchants of London Trading in the East Indies' was established, which in a decade organized as many as three expeditions to distant shores. Traders were primarily interested in spices, which were worth their weight in gold in European markets. Tea and cotton were also exported with no less joy.
Having evolved into the British East India Company, it took on new functions, military and governmental, snatching them out of the hands of the French, Portuguese and Danes by cunning, bribery or simply by arms. With the local rajahs, who were always at war with each other, the British used the same scheme.
Thus, by 1840, England had established unlimited power in its Indian colonies, massively siphoning off resources for the benefit of the newly rich nabobs who had made their fortune by plundering the local population.