Why is there almost no tribalism during Tanzanian elections?

Many African countries have experienced violence and intimidation during elections often caused by tribalism.

Tanzania which is heading towards one of its most anticipated general elections in many years this Sunday, is a different case

Tribalism is almost non-existent.

How has a country of more than 100 tribes succeeded in a region where many of its neighbours, including Rwanda, Kenya and Somalia, have experienced numerous cases of tribal-tension?

Zuhura Yunus reports.