The art of making tattoos is tattooing. Thai tattoos, also known as Yantra tattooing, was common since ancient times. Tattoos had negative connotations in historical China, where criminals often had been marked by tattooing. HIV may be transmitted through contaminated needles used in tattooing, body piercing, or injections. The trend of piercing or tattooing the navel became popular in the 1990s. Samoans have practiced the art of tattooing men and women for over 2,000 years. Corneal opacities are the leading reason for undergoing cosmetic tattooing. Scholars link labial elongation with genital tattooing. Some Ibans call this art of tattooing or . Sailor Jerry made significant contributions to the art of tattooing. Facial tattooing was also very common. Safety precautions for microblading are similar to those for any other tattooing technique. In the United States there is no federal law regulating the practice of tattooing. The Inuit People have a deep history of tattooing. This was the start of a lifelong interest in the practice of tattooing.