The only South Asian city that topped 1 million in 1800 or 1900 that is not mapped is Kolkata (then called Calcutta) in West Bengal (which I group with nearby states). (This area is covered for other periods--just not this one.) Kokata started with less than 400 thousand and was in the 1.0 to 1.999 million range by century's end. Its growth was due to it being the capital of British India, to it being the main export port for the British trade in opium, and to its growing industrialization in the second half of the century.