Tropical savanna climate
In the Middle Ages, Sumba were active in trading valuable species of wood and fragrant resin. Due to the merchants from Arabia to the island, new breed of horses were introduced. The dry climate of the local Tropical savanna climate contributed to the expansion of horse breeding. It is assumed that Sumba people were dependent on the Javanese kingdom of Majapahit, then from other kingdom relations in Sumbawa and Sulawesi. In fact, the power was divided among the local leaders, with their never-ending struggle for power. This has resulted in the development of slavery.