This tattooing tradition started centuries ago, when Chin tribes started tattooing the girl's face to avoid them from be captured as slave by the men from other tribespeople. It was made illegal it the 1960's although the tradition continue in some more remote villages until the 80's.
As soon as the girls enters the age of puberty, tattoo is applied onto her face – the pattern of the tattoo being the one according to the tribe she belongs. The process of facial tattooing is quite painful and dangerous. Some even died of infection. The practice has been outlawed since 1960s, but some still practiced in remoter areas until around 1980s, nowadays you will only find the elder women tattooed.