Africa, Asia, and Europe. For a brief history on this use, read this henna-pledia.
Henna for lasting nail color
Henna color has a permanence that conventional nail polish lacks. The color does not chip prematurely but lasts until the nail grows out fully.
Henna for stronger nails
Henna binds to the keratin in nails thus strengthening the nails.
Henna coloring instructions
Read this recipe and instructions for painting one's nails with henna. Various colors can be achieved, including red, burgundy, black, turmeric, and others depending on the henna mixture.