Southwest Uganda was already a colony when Britain arrived
When Bantu and Nilotic peoples met in northern, eastern, Buganda, Bunyoro and Toro they intermarried extensively and produced new communities and mixed economies of crop cultivation, herding and manufacturing. However, by the time the Nilotic Bahima (and later Batutsi under the new name of Bahororo) entered southwest Uganda (former Ankole district and Rujumbura county of Rukungiri district) they had decided against intermarriage with Bantu people and against allowing Bantu to own cattle as a form of capital accumulation. Nilotic Bahima and Bahororo people who were more powerful militarily but less advanced economically than Bantu chose to colonize the latter. By and large, colonization involves the colonizer depriving the colonized of their properties, disrupting their economic structures and imposing taxes or tribute in exchange for unsolicited law and order or protection.
For easy reference we need to know that before Nilotic people arrived in what later became southwest Uganda some six hundred years ago, Bantu people had developed dynamic and viable economic structures and systems that combined wild hunting, fishing and gathering, crop cultivation, livestock herding (short-horn cattle, goats and sheep) poultry rearing and manufacturing a wide range of products mostly based on iron ore. Food surplus and specialization had permitted the emergence of a ruling class of kings and chiefs or council of elders and a form of centralized governance system and diplomatic relations among different communities. In short, Bantu were civilized.