Sotho / Zulu violence

One of my long-standing theories is that more often than not, sworn enemies will come together to fight a common foe. I thought I'd long concluded that it was the case in Africa, where internal squabbles died off as nations fought colonialism. My theory leads me to believe that if we were suddenly attacked by little, green men wielding powerful laser guns, we would come together as earthlings? to defend our planet. It has been proven by the present situation in Iraq, where local groups have joined forces against the United States and its allies. But it has also been disproved by a myriad of other situations today and in the past. There are peoples who, for nothing in the world or even beyond, are willing to bury the hatchet. Why not? Please shrug, and turn your mouth into a downfacing "C". Blacks in southern Africa fought against apartheid long enough to have learnt the benefits of pulling together. Please place your index finger on your lower eye-lid and gently pull down. Why? Because
A weekend of violence between isiZulu- and seSotho-speaking residents in a Howick informal settlement escalated into a full-blown war on Sunday night, as dozens of houses and shacks were razed to the ground by arsonists in revenge attacks.

At least seven isiZulu-speaking residents were admitted to hospital on Saturday. Five of them were treated and discharged by Sunday after suffering serious injuries inflicted with sticks and sharp objects. [ Source... ]
There goes my theory. Consider the Balkans, look at Rwanda and Burundi. When are those little, green men coming? I'm tempted to loosely quote Quincy Jones, as I often do, who in turn quoted Marlon Brando as having said something like, "If we all had the same religion, the same colour, the same nationality and the same culture, the right-handed ones would start killing the left-handed ones." One can almost understand killings explained away through religion, or land-grabbing, or even race. But, language? Culture? What are those people in Howick, Kwazulu, fighting about? Is it a carry-over from the Lifaqane?
Mfecane (isiZulu), also known as the Difaqane or Lifaqane (Sesotho), is an African expression used about chaos and disturbances. It probably means something like "the Crushing", and originates from the events leading to the rise to power of chief Shaka. This Zulu chief conquered the Nguni peoples between the Tugela and Pongola rivers in the beginning of the 19th century, and created a militaristic kingdom. [ Source... ]