Mehndi is the application of henna as a temporary form of skin decoration in India, Pakistan and Bangladesh as well as byexpatriate communities from those countries. The word mehndiis derived from the Sanskrit word mendhikā. The use of mehndi and turmeric is described in the earliest Vedic ritual books. Haldi(Staining oneself with turmeric paste) as well as mehndi are important Vedic customs as a symbolic representation of the Outer and the Inner Sun. Vedic customs are meant to awaken the "inner light" and so the gold of the inner Sun has an important symbolic function!
Traditional mehndi designs draw the sun on the palm, which in this context represents the mind. this article is thank fully from Wikipedia .