The name Yei was given to the location where the current city stands by three traditional chiefs, one each from the Pojulu, Gimunu and Azande ethnic groups. The chiefs also conferred the name to the river that flows through the area and is now called River Yei. The three above ethnic groups had a traditional rivalry with the Kakwa, who also occupy neighbouring parts of Uganda and DRC. The first three ethnicities traditionally were found in what today is called "Mukaya Payam", while the Kakwa were found in "Marakonye Payam". They lived in co-existence with other smaller ethnicities, having rivalries from time to time.