This study commenced during a visit to Cambodia in 1994 when I became intrigued by statues and paintings of a beautiful young woman wringing water from her long hair under the Buddha's throne. I learned that her name was "Lady Earth," that she was associated with both the earth and the water, and that she received a cult. I also discovered that her story was part of the Buddha's biography. Just prior to the Enlightenment, Mara the evil one tried to prevent the Bodhisattva from reaching his goal. During his struggles with Mara, the Bodhisattva touched the earth (the bhamispariamudra) and called on the earth to be his witness against Mara. Although no textual source for the hair-wringing earth deity has yet been identified outside of mainland Southeast Asia, her iconography and story are too ancient and widely distributed across the cultures of the mainland to be attributed to one particular location. Today the earth deity can be found guarding the vajrasana in Arakan, Burma, Cambodia, Kampuchea Krom, Central and Northern Thailand, Laos, and Sipsong Panna in Yunnan. It has been necessary to devise a methodology that can cope with the many different countries, cultures, languages where the earth deity is found. I have found that focusing on the motif of the earth deity, in Buddhist art, the Buddha's biographical tradition, and performative texts (donative inscriptions, sadhana, paritta, mantra, yantra) is an effective strategy. I also look at myths and stories about the earth deity and aspects of the contemporary cult of the earth deity gleaned from fieldwork in Cambodia and Thailand.