Why do the tonga people of zambia call the zambezi river the "river of life"?

The river provides them with drinking water fish and irrigation for farming

One local folk law is that the Zambezi River has a spirit called Nyami Nyami – this spirit brings them water to grow their crops and fish to eat – and so they call the river “the river of life”. It then turns easterly and forms the border between Zambia and Namibia this is at the Katima Mulilo rapids

Explanation:

yes he did writing dots to make the answer