Considerable controversy surrounds the topic of the history and origins of the Shilluk. Indeed, the "origin" and history of all of the Nilotic peoples of the southern Sudan remains an enigma in the field of African prehistory. According to Shilluk oral traditions, the early descendants of these people began to migrate into their present country some three to four hundred years before the present. The quasi-mythical or epic leader of the first settlement is known as Nyikang, an individual with both divine and secular powers. At one time, Nyikang and his brother Gilo had a disagreement, and, as a result, Gilo and his supporters separated to migrate south and east. Like Nyikang for the Shilluk, Gilo is now cited as the culture hero and founder of the Anuak. Anthropologists posit that, before they arrived in their present country, the Shilluk practiced a nomadic form of pastoralism. As they eventually spread out and settled in more permanent communities, a horticultural mode of livelihood eventually replaced their primary dependence on cattle.