Before arrival of the colonial rulers, the Massailand spread over a vast area from north Kenya to the steppes to northern Tanzania. This gradually shrank due to the following reasons.
(i) The colonial powers were hungry for colonial possessions in Africa. Once they reached Africa, they began to cut it down in different colonies. Maasailand was cut into half with an international boundary between British Kenya and German Tanganyika.
(ii) The best grazing lands were gradually taken over for white settlement. Maasai were pushed into a small area in south Kenya and north Tanzania.
(iii) The colonial governments promoted cultivation. Local peasant communities began to take control over the pastoral land. Pastoral lands further fell.
(iv) Large areas of land were also turned into game reserves. Very often these reserves were in areas that had traditionally been regular grazing grounds for Maasais.