opium production, which is channelled into the black market. The headquarters of India's Central Bureau of Narcotics is in Gwalior. The Rajputana-Malwa Railway was opened in 1876. The region is predominantly agricultural. The brown soil in parts of the region is particularly suitable for the cultivation of such unalu (early summer) crops as wheat, gram (Cicer arietinum) and til (Sesamum indicum). Relatively poor soil is used for the cultivation of such syalu (early winter) crops as millet (Andropogon sorghum), maize (Zea mays), mung bean (Vigna radiata), urad (Vigna mungo), batla (Pisum sativum) and peanuts (Arachis hypogaea). Overall, the main crops are jowar, rice, wheat, coarse millet, peanuts and pulses, soya bean, cotton, linseed, sesame and sugarcane. Sugar mills are located in numerous small towns. The black, volcanic soil is ideal for the cultivation of cotton, and textile manufacture is an important industry. Large centres of textile production include Indore, Ujjain and Nagda. Maheshwar is known for its fine Maheshwari saris, and Mandsaur for its coarse woollen blankets. Handicrafts are an important source of income for the tribal population. Coloured lacquerware from Ratlam, rag dolls from Indore, and papier-mâché articles from Indore, Ujjain and several other centres are well known. Mandsaur district is the sole producer in India of white- and red-coloured slate, used in the district's 110 slate pencil factories. There is a cement factory in . Apart from this, the region lacks mineral resources. The region's industries mainly produce consumer goods—but there are now many centres of large- and medium-scale industries, including Indore, Nagda and Ujjain. Indore has a large-scale factory that produces diesel engines. Pithampur, an industrial town 25 km from Indore, is known as the Detroit of India for its heavy concentration of automotive industry. Indore is recognised as the commercial capital of Madhya Pradesh, and is the main centre for trade in textiles and agro-based products. It has one of the six Indian Institutes of Management and one of sixteen Indian Institute of Technology. Culture The culture of Malwa has been significantly influenced by Rajasthani culture, because of their geographic proximity. Marathi influence is also visible, because of recent rule by the Marathas. The main language of Malwa is Malvi, although Hindi is widely spoken in the cities. This Indo-European language is subclassified as Indo-Aryan. The language is sometimes referred to as Malavi or Ujjaini. Malvi is part of the Rajasthani branch of languages; Nimadi is