The Luo, part of the River-Lake Nilotics, are related to the Nuer and Dinka of Sudan. Their ancestral homeland is believed to have been in Rumbek, southern Sudan. During the 15th century, a series of calamities, including overpopulation, diseases affecting humans and animals, droughts, floods, pressures from the Galla tribesmen, and internal conflicts, compelled the Luo to migrate in search of new settlement areas.

Some Luo groups moved north to Shilluk, others east to Anuak, and some continued through Ethiopia to northern Uganda. The largest group is said to have moved southwards along the Nile to Pubungu near Pakwach under the leadership of Olum.

Olum had three sons: Gapiir (Nyapir), Labongo (Kyebambi), and Tiful. At Pubungu, a dispute over the royal spear—a symbol of power—between Gapiir and Labongo led to their separation. Gapiir crossed the Nile and settled among the Lendu and Okebu in present-day West Nile, intermarrying with them and forming the Alur. The Alur continue to speak Luo and maintain aspects of Luo culture. Tiful also moved to West Nile, but details about his subsequent movements and settlements are sparse.

Labongo’s group migrated north-east from Pubungu into present-day Acholi, intermarrying with Sudanic-speaking peoples in northern Uganda, and formed the Acholi. By the early 18th century, they were well-established in Acholi. Conflicts with the Langi, who had been settled in Acholi for about two centuries, forced the Langi to move south to the Lake Kioga region. Over time, the Langi assimilated with the Acholi, adopted the Luo language, and transitioned from pastoralism to agriculture due to the region’s unsuitability for pastoral activities. Though they speak Luo, the Langi are more accurately described as Nilo-Hamites.

Another Luo faction moved south from Pubungu to Pawir, an area now inhabited by the Bagungu. A subgroup led by Isingoma Mpuga Rukidi settled in Bunyoro, establishing the Babiito dynasty. This new kingdom, known as Bunyoro-Kitara, lasted until 1967 when Milton Obote’s new constitution abolished kingdoms and established a republic. The Luo settlers in Bunyoro were assimilated, losing their language and culture, but they left a legacy of pet names among the Banyoro. The relationship between the Bachwezi and the Babiito remains unclear, despite some traditional claims of connection.

Between the mid-16th and early 17th centuries, additional Luo groups migrated eastwards. Led by Adhola, one group settled in Budama in the early 17th century, choosing a forested area for protection against Bantu neighbors. This isolation helped them preserve their language and culture despite the surrounding Bantu and Ateker communities. From 1550 to 1800, other Luo groups moved into Kenya’s Nyanza Province. By 1800, the Luo had completed their migration and settled in present-day northwestern, northern, and eastern Uganda.