Pre-colonial Rwandan society is made up of three social groups - the Tutsi, the Hutu and the Twa.
The Tutsi are a cattle-rearing elite who, although a minority, form the dominant class and establish a mostly peaceful, feudal-style monarchy headed by a Tutsi king.
The Hutu are "commoner" farmers who make up over 80% of the population and serve the Tutsi "aristocracy".
However, barriers between the two groups are fluid. Hutu are able to rise to positions of authority within the feudal system and attain Tutsi status. Tutsis may lose status and fall back in with the Hutu majority. Both groups share a common culture, language and religion and occasionally intermarry.
The Twa are a forest-dwelling people whose occupation of Rwanda is thought to predate both the Tutsi and the Hutu. They comprise only about 1% of the population.
Landlocked and inaccessible, Rwanda is one of the last areas of Africa to be exposed to Europeans.
The first known European to reach the country is German Count Von Goetzen in 1894. European control is instituted soon after, with the Tutsi king allowing Germany to establish a protectorate over the country in 1899. Following the outbreak of the First World War in 1914 the Germans are chased out by troops from the neighbouring Belgian Congo.
After the war the League of Nations, the forerunner to the United Nations (UN), confirms Belgian control.
The Belgians formalise and simplify the existing social system in order to ease administration of the colony. Only Tutsi are allowed to become officials. Hutus are removed from positions of power and excluded from higher education. They are organised instead as a labour-force to be supervised by Tutsi overseers.
In 1933 the group divides are entrenched when all Rwandans are registered as Hutu, Tutsi or Twa and issued with a racial identity card. To implement the system, each individual is asked to define their group identity. About 15% of the population declare themselves as Tutsi, approximately 84% say they are Hutu, and the remaining 1% identify as Twa.
The colonial system serves to polarise Rwandan society. While the Tutsi elite comes to see itself as superior with a right to rule, the Hutu come to see themselves as an oppressed majority.