Numbering approximately 23 million worldwide, Sikhs make up 0.39% of the world population of which approximately 83% live in India. Of the Indian Sikh community 14.6 million, i.e. 76% of all Indian Sikhs, live in the northern Indian State of Punjab (India), where they form a majority 59.9% of the population. Substantial communities of Sikhs, i.e. greater than 200,000, live in the Indian States of Haryana, Rajasthan, Uttar Pradesh, Delhi, Maharashtra, Uttaranchal and Jammu and Kashmir.
Sikh migration from the then British India began in earnest from the 2nd half of the 19th century when the British had completed their annexation of the Punjab. The British Raj preferentially recruited Sikhs in the Indian Civil Service and, in particular, the British Indian Army, which led to migration of Sikhs to different parts of British India and the British Empire. During the era of the British Raj, semiskilled Sikh artisans were also transported from the Punjab to British East Africa to help in the building of railways. After World War II, Sikhs emigrated from both India and Pakistan, most going to the United Kingdom but many also headed for North America. Some of the Sikhs who had settled in eastern Africa were expelled by Ugandan dictator Idi Amin in 1972. Subsequently the main 'push' factor for Sikh migration has been economic with significant Sikh communities now being found in Canada, the United Kingdom, the United States, Malaysia, East Africa, Australia and Thailand.
Whilst the rate of Sikh migration from the Punjab has remained high, traditional patterns of Sikh migration, that favored English speaking countries, particularly the United Kingdom has changed in the past decade due to factors such as stricter immigration procedures. Moliner(2006) states that as a consequence of the 'fact' that Sikh migration to the UK had "become virtually impossible since the late 1970s", Sikh migration patterns altered to continental Europe. Italy has now emerged as a fast growing area for Sikh migration, with Reggio Emilia and the Vicenza province being areas of significant Sikh population clusters. The Italian Sikhs are generally involved in areas of agriculture, agro-processing, machine tools and horticulture.
Due primarily to socio-economic reasons, Indian Sikhs have the lowest adjusted decadal growth rate of any major religious group in India, at 16.9% per decade (est. 1991–2001). Johnson and Barrett(2004) estimate that the global Sikh population increases annually by 392,633 Sikhs, i.e. by 1.7% p.a. on 2004 figures, this growth rate takes into account factors such as births, deaths and conversions