The tilaka – a mark/design on the forehead – has a long history in India. Vermilion and Kumkum/Sindoor (often reddened turmeric) are mentioned in old texts but so are facial designs made from pastes containing sandalwood (a particular favourite), musk and saffron.
There is nothing definite to indicate that it was more than a cosmetic aid or that the design must be a red dot or that it denotes marital status in women.
By the 20th century of course in most orthodox Hindu communities sindoor denoted marital status (barring communities like the Brahmos and other reformist groups in the 19th/20th century) though modern variants are often used purely for decorative purposes.
This photograph is of Indian film actress, Rehka. Writing of Rehka’s biography, The Times of India wrote “Be it wearing sindoor fearlessly to an award function or shooting a steamy scene with a co-star who is almost 20 year younger to her to grabbing all the attention by hugging Jaya Bachchan while Amitabh getting awarded for his outstanding performance, Rekha has always been untamed, spontaneous, strong and fearless.