Scholarly[153][154][155] and U.S. Department of State sources[38] state that a majority of southern Sudanese maintain traditional indigenous (sometimes referred to as animist) beliefs with those following Christianity in a minority.

The Federal Research Division of the US Library of Congress states that "possibly no more than 10% of southern Sudan's population was Christian".[157] In the early 1990s, official records of Sudan claimed that the population of what was then included as South Sudan, 25% of people followed traditional religions and 5% were Christians.[158]

Also, if you read the article, you’d know this is a thousands of years old African tradition.