The next small groups of Nepalese emigrated primarily from eastern Nepal under British Indian auspices in the late nineteenth and early twentieth centuries. Members of many ethnic groups, including forefathers of Lhotshampa and others from Sikkim, the Assam Duars, and West Bengal, were brought into Bhutan as slaves (the institution was abolished in 1958). Seasonal migrants commonly worked in the Bhutan Duars, and began to settle in the 1880s. During the late 19th Century, contractors working for the Bhutanese government began to organise the settlement of Nepali-speaking people in uninhabited areas of southern Bhutan in order to open those areas up for cultivation. The south soon became the country's main supplier of food. By 1930, according to British colonial officials, much of the south was under cultivation by a population of Nepali origin that amounted to some 60,000 people.