Tutsi rule. The Tutsi aristocracy or elite was distinguished from Tutsi commoners, and wealthy Hutu were often indistinguishable from upper-class Tutsi. When the Belgian colonists conducted censuses, they wanted to identify the people throughout Rwanda-Burundi according to a simple classification scheme. They defined "Tutsi" as anyone owning more than ten cows (a sign of wealth) or with the physical feature of a longer nose, or longer neck, commonly associated with the Tutsi. The Belgians believed that some Tutsis had facial characteristics that were generally atypical of other Bantus. They sought to explain these purported divergent physical traits by postulating admixture with
Rwandan genocide or simply having a "Tutsi appearance". The RPF was making slow but steady gains in the north and east of the country, ending the killings in each area occupied. The genocide was effectively ended during April in areas of Ruhengeri, Byumba, Kibungo and Kigali provinces. The killings ceased during April in the "akazu" heartlands of western Ruhengeri and Gisenyi, as almost every Tutsi had been eliminated. Large numbers of Hutu in the RPF conquered areas fled, fearing retribution for the genocide; 500,000 Kibungo residents walked over the bridge at Rusumo Falls, into Tanzania, in a few days at the end