Ukwa was a mythic ancestor.
In the beginning was Juok, the great creator; he created a great white cow, called Deung Adok, that came up out of the Nile. The cow gave birth to a man-child, whom she nursed and named Kola. Kola begat Umak Ra, or Omaro, who begat Makwa, or Wad Maul, who begat Ukwa. These people lived in a far-off country, nobody knows where.
Ukwa was one day sitting near the river when he saw two beautiful women with long hair rise out of the river and play about in the shallows. He saw them many times after that, but they would have nothing to do with him, merely laughing at him. Their lower extremities were like those of a crocodile. One day when Ukwa found them sitting on the banks, he came up behind and seized them. Their screams brought their father, Ud Diljil, out of the river to see what was the matter. Ud Diljil, whose right side was green in color and in form like a crocodile, while his left side was that of a man, protested mildly, but he allowed Ukwa to take away his daughters and wed them, at the same time uttering a series of prophecies. Nik-Kieya, the elder sister, gave birth to two sons and three daughters, and Ung-Wad, the younger, to one son only, named Ju, or Bworo. The eldest son of Nik-Kieya was called Nyikang; he inherited the crocodile attributes of his mother and grandfather. Meanwhile, Ukwa married a third wife, whose eldest child, a son, was named Duwat. On Ukwa's death, there was a quarrel between Nyikang and Duwat as to who should succeed Ukwa. It ended by Nyikang, with his sisters, Ad Dui, Ari Umker, and Bun Yung, his brother, Umoi, and his half brother, Ju, acquiring wings and flying away to the south of the Sobat (Bahr El Asraf). They found the Shilluk country inhabited, so they drove the people out and founded a successful kingdom. See also: Juok, Nyikang.