But the lone Muslim-majority district exists not in UP, which has a strong Muslim concentration in Oudh and Rohailkhand. Instead, the district is located in Haryana. Mewat that has a population of nearly 1 million or 9.9 lakh has over 70% Muslims.
Though Haryana has just 6% Muslims, the Mewat region has a predominant Muslim population. In the year 2005, Mewat was constituted as the 21st district of the state. Earlier it was part of the Gurgaon district, which is close to Delhi.
Mewat is populated by Meos (Mev) who for centuries remained Muslims but also followed Hindu practices. This area was a battle field between Shuddhi movement workers and the Tablighi Jamaat activists before and after independence.
While Uttar Pradesh has around 19% Muslims followed by Bihar (17%), Rajasthan (8%), Madhya Pradesh (7%), Delhi (12%), the lone district that has such a large Muslim population exists in Haryana. UP's Rampur has also nearly 50% Muslims.
Bihar's Kishanganj has even higher percentage but geographically it lies in Eastern India, on the border of West Bengal state. Mewat has been a backward region and educational levels are low here. Efforts are on to improve literacy rate in this district.
UPDATE: This is an old post. After Census 2011, which was conducted and its report was released a few years later, Uttar Pradesh also has been a state with Muslim majority district--Rampur. Smaller districts that were created later, also have a high Muslim population, but no Census was conducted after 2011.