Photographs of dancing girls/courtesans taken during the late 19th/early 20th century demonstrating regional costumes. Lots of anklets:)
Pic 1 is of a Tamil dancing girl (I think the sari was probably a nine yard and the pallu is belted at the waist and allowed to fall); Pic 2 maybe from Bengal (Calcutta was mad for nautch in the 19th century but many dancers came from afar, often the costumes are Northern - though you can count on Kalighat painters for a local flavour), again Pic 3 could be Bombay or Calcutta given the sari and blouse and they do love shoes, Pic 4 is from Maharashtra given the sari style. Pics 5 to 7 are all possibly of Northern/Lucknowi nautch girls. The Lucknow nautch girls deserve an entire post - their photographs indicate that they were every bit as alluring and sassy as suggested by this paper.
For the most part costume is regional (see for example Kashmiri nautch girls or Telugu dancing girls) with sari styles worn in the South and full skirted ghaghra styles in Gujarat and Rajasthan. In the north, there is an astonishing variety in the tunic/trouser kind of dress from very short tunics to voluminous anarkalis to very wide trousers to the outfit we more commonly see today depending on the place and decade.
Sources: (X), (X), (X)