From the mid-16th century to mid-17th century, the jeogori was quite long, more like a proper coat than the little jacket it is now, maxing at 78 cm in lenght measured from the shoulder. However, from 1650’s on, the hem started shortening and shortening, reaching the shortness of only 20 cm in late 19th century. At this point it no longer covered the breasts, and while the skirtband of the chima had also climbed with the hem of the jeogori, it now fastened just under the breasts instead of the natural waist. Because of this, women came to adopt a piece of clothing called heoritti, which they would tie around their bosom. Originally the heoritti appears to have been plain white, but later, seeing as they were exposed, they grew more decorated.
However, at some point around the end of the Joseon dynasty, women of the lower classes would stop wearing the heoritti altogether.
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