Map - Thane district (Thane)

Thane district (Pronunciation: [ʈʰaːɳe], previously named Taana or Thana) is a district in the Konkan Division of Maharashtra, India. At the 2011 Census it was the most populated district in the country, with 11,060,148 inhabitants; however, in August 2014 the district was split into two with the creation of a new Palghar district, leaving the reduced Thane district with a 2011 Census population of 8,070,032. The headquarters of the district is the city of Thane. Other major cities in the district are Navi Mumbai, Kalyan-Dombivli, Mira-Bhayander, Bhiwandi, Ulhasnagar, Ambarnath, Badlapur, Murbad and Shahapur.

The district is situated between 18°42' and 20°20' north latitudes and 72°45' and 73°48' east longitudes. The revised area of the district is 4,214 km2. The district is bounded by Nashik district to the north east, Pune and Ahmednagar districts to the east, and by Palghar district to the north. The Arabian Sea forms the western boundary, while it is bounded by Mumbai Suburban district to the south west, and Raigad District to the south.

In 1817, the territory now comprising Thane district was taken over by the British from the Peshwa and it became a part of North Konkan district, with its headquarters in Thana. Since then, it has undergone considerable changes in its boundaries. In 1830, the North Konkan district was expanded by adding parts of South Konkan district and in 1833 was renamed Thane District. In 1853, the three sub-divisions of Pen, Roha and Mahad together with Underi and Revadanda agencies of Kolaba were formed into the sub-collectorate of Kolaba, under Thana, and ultimately were separated to become an independent Kolaba district in 1869 (now known as Raigad district).

Back in 1866, the administrative sub-divisions of Thane were reorganised and renamed: Sanjan as Dahanu, Kolvan as Shahapur and Nasrapur as Karjat. Vada petha was upgraded to the level of a taluka. Uran Mahal was separated from Salsette in 1861 and was placed under Panvel. Panvel, together with its mahals of Uran and Karanja, was transferred to Kolaba district in 1883 and Karjat was transferred in 1891. A new mahal with Bandra as headquarters was created in 1917 and in 1920 Salsette was divided into two talukas — North Salsette and South Salsette. South Salsette consisting of 84 villages was separated from Thana District and included in the newly created Bombay Suburban district (present Mumbai Suburban district). North Salsette was made a mahal under Kalyan taluka in 1923 and renamed as Thane in 1926. Kelve-Mahim was renamed as Palghar. 33 villages of the Bombay Suburban district were transferred to Thana district in 1945 and 14 of them were re-transferred to the Bombay Suburban district in 1946 when the Aarey Milk Colony was constituted.

After Independence, in 1949, the Koli princely state of Jawhar was merged with Thana district and became a separate taluka. As many as twenty-seven villages and eight towns from Borivali taluka and one town and one village from Thana taluka were transferred to the Bombay Suburban district in 1956 when the limits of Greater Bombay were extended northwards in Salsette. In 1960, following the bifurcation of the bilingual Bombay State, 47 villages, and three towns in the taluka of Umbargaon were transferred to Surat district in Gujarat and its remaining twenty-seven villages were first included in Dahanu and later in 1961 made into a separate mahal, Talasari. In 1969, the taluka of Kalyan was divided into two talukas, Kalyan and Ulhasnagar.