By the 15th century, the various Zulu chiefdoms had reached the south-eastern part of Southern Africa. They were largely cattle farmers and cultivators who lived in scattered villages across the land. Like other African peoples at this time, they lived within a system of clans and tribes under independent chiefs until, in the latter part of the 18th century, the system changed, possibly due to land shortage, and a number of larger political groupings were formed. The most powerful among these were the Mthethwa under the leadership of Dingiswayo, who radically changed some aspects of traditional life during his reign.
Formerly, military activity was based on local recruitment; men from a district would fight together under their chief. So, in order to create a large unified fighting force and control the fierce rivalry between supporters of different groups, Dingiswayo reorganized his army along the lines of age rather than old local allegiances. Thus, men of a particular age group, regardless of clan or residence, formed a regiment whose loyalty was to the king alone. Fathers and sons fought in different regiments and men from the same district found themselves in completely different groups, and as a result local rivalry was prevented. This was the basic military system that Shaka, the most famous Zulu chief, inherited and built on.