The opium trade yielded enormous profits to the British imperialists during the nineteenth century and the first half of the twentieth century.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/historical-overview-opium-cultivation-and-changing-state-attitudes-towards-crop
[2] http://admin.indiaenvironmentportal.org.in/category/author/anirudh-deshpande
[3] http://admin.indiaenvironmentportal.org.in/category/journal/studies-history
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/agriculture
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/trade
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/narcotics
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/legislation
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/history
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/india
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/arunachal
[12] http://admin.indiaenvironmentportal.org.in/category/thesaurus/assam
[13] http://admin.indiaenvironmentportal.org.in/category/thesaurus/uttaranchal-uttarakhand
[14] http://admin.indiaenvironmentportal.org.in/category/thesaurus/statistics