The Butua state was one of the largest pre-colonial state systems, established in southern Africa in the early 15th century. The state was initially centered at Khami but the capital moved to Danamombe in the 17th century. A defining characteristic of the Butua state was its architecture, which is predominantly made up of terraced platforms built using the technology of dry-stone masonry. The state covered a large area that includes modern-day southern and south-western parts of Zimbabwe, north-east Botswana, and northern South Africa. The Butua state thrived on a number of key economic activities that included mining of various minerals, including gold, which was in high demand from Portuguese and Swahili traders on the Indian Ocean coast. Various metals were also processed to provide a range of utilitarian or ornamental objects made of gold, copper, iron, or alloys of more than one metal. Other economic pillars of the Butua state included cattle farming, agriculture, and local exchange of commodities as well as participation in global exchange networks through the Indian Ocean.
Climate has emerged as one of a number of themes in debates concerning the formation and disaggregation of African state structures before the colonial era. The proliferation of paleoclimatic data series from “natural archives” such as tree-rings has shed increasing light on changes in temperature and precipitation stretching back millennia. Such long-term climatic changes could have enduring effects on human livelihoods in agriculturally marginal areas. The apparent coincidence of periods of climatic change with major turning points in African history over the last millennium has therefore led to claims of causation, with early moves towards state formation in the Shashe–Limpopo basin (c. 1000–1220ce) and in KwaZulu-Natal (c. 1750–1800) linked to contemporaneous warm–wet conditions, and the decline, or “collapse,” of state structures, including Mapungubwe (c. 1300ce) and Great Zimbabwe (c. 1450ce), linked to a shift to cooler and drier regional climates. Recent literature from both within and outside of the southern African context has begun to question the veracity of climate-driven historical change. In the southern African case, there remains considerable uncertainty concerning the climate history of the region prior to 1800. The climatic signatures captured by some records are ambiguous in their representation of temperature or precipitation, while many long-duration climate records available for southern Africa are simply of insufficient temporal resolution to capture the short-term extremes in rainfall that have proved challenging to societies in more recent centuries. Even where there is robust evidence for the coincidence of wet or dry conditions with societal change, African farming communities were far from passive observers, but responded to environmental stress in a variety of ways. The relative length, continuity and richness of the historical record in Zimbabwe and Mozambique after. c. 1505 provides opportunities to look more closely at these relationships. From the early 16th century onwards, Portuguese observers left records of those droughts which most impacted societies. These short-term extremes—usually back-to-back years of deficient, irregular or delayed rainfall, sometimes coupled with locust plagues—had varying effects between and within societies as they were “filtered” through different levels of societal vulnerability and resilience, which in turn engendered divergent responses. Analysis of over three centuries of written records on the pre-colonial period suggest that climate-related stress alone, while sometimes leading to famine, was rarely enough to cut deeper into the political fabric of the region; yet, when combined with weak institutional capacity, warfare, or increasingly uneven distributions of power, extreme and protracted droughts could prove decisive and help bring about transformations in society. The Mutapa state and lower Zambezi valley during the late 16th and early 19th centuries, as well as the Zulu kingdom in the 1820s, serve as cases in point.