Mulugu (Telangana): The four-day 'Maha Jathara' of tribal goddesses Sammakka and Saralamma, dubbed as one of the largest Adivasi spiritual congregations in the world, got underway at Medaram in this district. An estimated three crore devotees are expected to attend the biennial 'Maha Jathara' this year, official sources said. A devotional atmosphere pervaded the 'Maha Jathara' site as some women devotees were "possessed" by the goddesses. Elaborate arrangements have been made for the 'Maha Jathara' that began about six months ago. The 'Maha Jathara' is celebrated in Medaram during the time the goddesses of the tribals is believed to visit them.