The Tutsi (ˈtʊtsi), also called Watusi, Watutsi or Abatutsi (ɑ.βɑ.tuː.t͡si), are an ethnic group of the African Great Lakes region. They are a Bantu-speaking ethnic group and the second largest of three main ethnic groups in Rwanda and Burundi (the other two being the largest Bantu ethnic group Hutu and the Pygmy group of the Twa). Historically, the Tutsi were pastoralists and filled the ranks of the warriors' caste. Before 1962, they regulated and controlled Rwandan society, which was composed of Tutsi aristocracy and Hutu commoners, utilizing a clientship structure. They occupied the dominant positions in the sharply stratified society and constituted the ruling class. The definition of "Tutsi" people has changed through time and location. Social structures were not stable throughout Rwanda, even during colonial times under the Belgian rule. The Tutsi aristocracy or elite was distinguished from Tutsi commoners. 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 features of a longer thin nose, high cheekbones, and being over six feet tall, all of which are common descriptions associated with the Tutsi. In the colonial era, the Tutsi were hypothesized to have arrived in the Great Lakes region from the Horn of Africa. Tutsis were considered by some to be of Cushitic origin, although they do not speak a Cushitic language, and have lived in the areas where they presently inhabit for at least 400 years, leading to considerable intermarriage with the Hutu in the area. Due to the history of intermingling and intermarrying of Hutus and Tutsis, some ethnographers and historians are of the view that Hutu and Tutsis cannot be called distinct ethnic groups. Origins of Hutu, Tutsi and Twa Modern-day genetic studies of the Y-chromosome generally indicate that the Tutsi, like the Hutu, are largely of Bantu extraction (60% E1b1a, 20% B, 4% E-P2(xE1b1a)).