Most of these figurines are naked, or nearly so, and have elaborate head-dresses. Excavations at Mehrgarh have been able to uncover a fairly continuous sequence in cultural change and the more elaborate the coiffure, the later the figurine, The earliest date back to the sixth or fifth millennia and are of unbaked clay and stick-like in character but, by the time of the Indus valley culture at about . the mid-third millennium, the figurines had become fairly sophisticated in style with the characteristic elaborately-coiled hair styles. This kind of evidence suggests a long tradition of worship, of the divine in female form, stretching well back before the time of the Indus valley civilization. Fertility was obviously an important issue in the religion of the people. One female figurine is upside down with a plant coming. out of the womb - an indication of the Mother Goddess as the genetrix and source of all vegetation. The idea is reminiscent of tantric Hinduism. For a culture based on agriculture a female divine principle would have been essential and reproductive energy. venerated. In later Hinduism, just as Siva is associated with the symbol of male sexuality, the linga, so female divinity is symbolized by the yoni, the female sex organ. It is possible that the ring-shaped images found throughout the Indus valley sites (except at Lothal) have some connection with the yoni symbolism, but the connection must remain speculative. The prevalence of female figurines in the home environment may suggest that worship of the Mother Goddess was something of a domestic phenomenon. Male deities, if such they were, seem, on the other hand, to have featured at all levels of culture.