Why Kalenjin parents don't allow their daughters to be married to Luos

We are in the car with my dad and my sister. My sister is at the back seat. She had erred. Apparently my dad had accessed her phone. He had seen all the messages she had been exchanging with everybody including me telling her to switch off her phone so that dad could buy her another one. She had been asking for a phone for a long time and I was suggesting a measure he could bow to. He did but at a price. Dad had forced her to surrender her phone so that he can get her a new one. As you can already guess the phone was in perfect condition.

My sister had been exchanging love messages with some Luo guy. Dad had seen it and he wasn’t that pleased. He adjusted his seat and gave her a sharp gaze and said without mincing his words: "NEVER SHOULD A LUO MAN COME INTO MY HOUSE ASKING FOR YOU."