Busoga, Bunyoro and Tooro are one family that grew too big for one house. Their story begins with the Kitara Empire around 1200. The ancestor was Ntonzi, and his grandson Isimbwa, son of Isaza, left Kitara to hunt north of the Nile in Luo land, today Acholi, Alur and Lango. There he met Nyatworo, also called Nyawudi, daughter of Labongo the Luo leader. He married her, she became pregnant, and he returned to Kitara.
Nyatworo gave birth to twins who founded two kingdoms. The first, Isingoma Rukidi Mpuga, was light-skinned like his Chwezi father. The second, Kato Kintu, was dark-skinned like his Luo mother and was called Kato because he was small. When grown, Rukidi went south, overthrew the last Chwezi king of Kitara and became Isingoma Mpuga Rukidi I, the first Mubiito Omukama of Bunyoro. All Banyoro and Batooro kings come from him, the Babiito dynasty that rules to this day. Kato Kintu went southeast and became Kintu, the first Kabaka of Buganda. So Bunyoro and Buganda are twin-brother kingdoms.
Busoga was born from Bunyoro. Bunyoro was very large, stretching from Lake Albert to Lake Victoria. Around the 1500s to 1600s, a prince left to look for salt and land. In Busoga history he is called Mukama Namutukula, but in Bunyoro he is Prince Kalemera, son of an Omukama. He crossed the Nile into what is now Busoga, found small chiefs called Bataka, married their daughters and had five sons. Those five sons founded the five original royal clans of Busoga: Gabula of Bugabula, Zibondo of Bulamogi, Ngobi of Kigulu, Tabingwa of Luuka, and Menkha or Wakooli of Bukooli. These chiefdoms became Busoga Kingdom. That is why Busoga has no single royal family like Buganda; it has five Babiito-related families who rotate the Kyabazingaship. The Omukama of Bunyoro is the uncle of Busoga's kings.
Tooro is the youngest brother, born from Bunyoro in 1822. Prince Olimi Kaboyo Kasunsunkwanzi, eldest son of Omukama Nyamutukura Kyebambe III of Bunyoro, rebelled. As eldest son from a lower-ranking mother, he was sent to collect taxes in the south in Tooro. He used that army to declare himself independent, crossed River Muzizi and settled in Fort Portal as Olimi I, first Omukama of Tooro. That is why Bunyoro and Tooro kings share the title Omukama, while Busoga's leader is Kyabazinga, though he was also called Omukama before the British. All three are Babiito.
To this day they feel like one people. They share the same ancestor, Ntonzi, Isimbwa and Labongo, a Bantu father and Luo mother. They share royal drum culture, like Bagaya and Nduru in Bunyoro, without which no king can rule. They share a clan system where you cannot marry from your own clan, stricter in Busoga where the five royal clans cannot intermarry. They share titles: Omukama in Bunyoro and Tooro, Kyabazinga in Busoga, and Katikkiro, Katuukiro or Omuhikirwa for prime minister. Their ceremonies are similar: Empango in Tooro and Bunyoro and the installation of the Kyabazinga in Busoga both involve sitting on leopard skin, eating a white cow and receiving a spear from the uncle clan. Their languages, Runyoro, Rutooro and Lusoga, share thirty to forty percent of old Chwezi words like Omukama, Omwana, Omukali, Amagezi and Ente. That is why you find a man in Fort Portal called Okwir Labongo, with a Luo name but a Tooro kingdom, just like a man in Iganga called Okwir Wakooli.
In short, Bunyoro is the father house founded by Rukidi, Busoga are the five grandsons who crossed the Nile earlier and built five small houses, and Tooro is the eldest son who left home in 1822. All are Babiito, all are children of Nyatworo and Kyomya, which is why they share drums, leopard skin and clans.