Its slow decline starting at the end of the 14th century followed internal discord and revolts by vassal states, one of which, Songhai, flourished as an empire between the 14th and 16th centuries. Songhai was also weakened by internal discord, which led to factional warfare. This discord spurred most of the migrations southward toward the forest belt. The dense rain forest covering the southern half of the country, created barriers to the large-scale political organizations that had arisen in the north. Inhabitants lived in villages or clusters of villages; their contacts with the outside world were filtered through long-distance traders. Villagers subsisted on agriculture and hunting.