The Rwandan population had designated identification cards with their race on it. This was introduced by the Belgian government beforehand. While Hutu and Tutsi groups were not originally ethnic groups in pre colonial times, they were different groups in the Rwandan and Burundian social structure, which also meant that individual Hutus could become a Tutsi and vice versa.

It was often the case however that Hutu and Tutsi members would follow similar professions to what their parents beforehand did, so while Belgian anthropologists concluded that the physical differences between the Hutu and Tutsi was based of the 'Hamitic hypothesis' (in that Tutsi ancestry was derived from Caucasian migrations into Africa) what they were actually looking at was physiological differences in populations as a result of profession and way of life (Tutsi predominantly having administrative roles, Hutu being more accustomed to labouring).