Before the Portuguese, who were the first Europeans in India, traded with India there was extensive trading for centuries by the Arabs between the west coast of India and southern Europe. The Indigo plant or dye was one of the items of trade.
These dyes - brilliant purple and reds - were very expensive and only the Roman Emperors and the very wealthy could afford them hence the term "the royal purple". The range from deep red to purple to deep blue can be obtained by adjusting the pH (acidity - alkanility) of the solution. It was the Portuguese who gave the dye or plant the name "Indigo" meaning "from the indies". The Arabs called the dye "a-nil" meaning "the blue" - they just used the adjective and left out the noun. "Nil" is blue in Sanskrit as in the Nilgiri Hills in Southern India which translated means the "Blue Hills" as they look blue from the plains due to the combination of mist and heavy rain forest.
In the late 1800's the Germans - and later the British - synthesized these indigo dyes chemically and used the original arab or Sanskrit name in calling them "anilin dyes" which is the term used in chemistry books. Unfortunately the chemical synthesis of these dyes by the Europeans effectively destroyed the indigo industry in India. During World War II in India we couldn't get the synthetic dyes or fabric from England; instead we used Indian fabrics dyed with the Indian indigo dyes.
- Index of Indigo Planters in Bihar taken from History of Behar Indigo Factories; Reminiscences of Bihar; Tirhoot and its inhabitants of the past. History of Behar Light Horse Volunteers by Minden Wilson 1908. (Fibis Database)
- 'The lure of Indigo - and how the Hills family of East Bengal won three VCs' FIBIS podcast by Miles McNair.
- "Adam Maxwell of Cawnpore-Indigo and Intrigue" by Judith Vandenburgh Green FIBIS Journal Number 25 (Spring 2011), pages 25-33
Historical books online
- Papers relating to the cultivation of indigo in the Presidency of Bengal 1860 Google Books
- Selections from the Records of the Government of Bengal No 33 part 2: Papers relating to indigo cultivation in Bengal, Volume 2 1860 Google Books
- East India: Indigo Commission Volume 11, Accounts and Papers of the House of Commons Session 5 February-6 August 1861 Google Books
- “Letter VIII: Mulnath Indigo Factory” from Rural life in Bengal: illustrative of Anglo-Indian suburban life, the habits of the rural classes, the varied produce of the soil and seasons, and the culture and manufacture of indigo : letters from an artist in India to his sisters in England by Colesworthey Grant 1866 illustrated with one hundred and sixty six engravings.
- Tent Life in Tigerland with which is incorporated Sport and Work on the Nepaul Frontier : being twelve years' sporting reminiscences of a pioneer (indigo) planter in an indian frontier district by James Inglis 1892. Sport and Work on the Nepaul Frontier was first published 1878 and commences page 369 Archive.org
- The culture and manufacture of indigo; with a description of a planter's life and resources by Walter Maclagan Reid 1887 Archive.org
- Report on the Cultivation and Manufacture of Indigo in Bengal 1899 Archive.org
- “Indigo” from A History of Murshidabad District (Bengal) : with biographies of some of its noted families by John Henry Tull Walsh 1902 Archive.org
- History of Behar Indigo Factories ; Reminiscences of Behar ; Tirhoot and its inhabitants of the past ; History of Behar Light Horse Volunteers by Minden Wilson 1908 Archive.org
- Bengal and Assam, Behar and Orissa: their history, people, commerce and industrial resources by Somerset Playne and J W Bond 1917 on the Archive.org website has a chapter on "Indigo in Behar" and "The Behar Planters Association, Ltd"
- Model of an Indian indigo factorybbc.co.uk
- Indigo from Plant Cultures includes information on plant history and production
- Decline of Indigo business in India from Merchant Networks
- This India List post advises that the word 'mookarrarie' which appears in History of Behar Indigo Factories means 'a permanent tenure'.