The war cry of Ceteshwayo's Zulu army. It refers to Ceteshwayo's tribal ancestry.
If you go back in time to about 1879, and you are in South Africa, and hear people shouting "uSuthu! uSuthu!", then you should run away. Some assegai-wielding Zulu warriors are about to come and wash their spears in your blood.
The Zulus practiced conscription, and their impis lived together and were highly trained in tactics. The army system, and many improvements in tactics, strategy, and equipment were made by King Shaka (or Chaka).
The formidible Zulu military was ultimately defeated by the British in the Zulu Wars.