Clothes made from indigo-dyed cloth. [Photo/VCG]

Natural indigo-dye has a long history in China, dating back to the Qin and Han dynasties (BC 221-220), and indigo-dyed cloth had been used as a main material for clothes for at least 1,000 years. In Chinese, any plant that can be used to extract indigo is generally called lan cao (literally, "blue plants").

The cloth dyed by these plants always retains a faint fragrant smell and is naturally mothproof. It can be made into clothes that are most suitable for summer.