The Hindi Belt or Hindi Heartland is a loosely defined linguistic region in north-central India where varieties of in the broadest sense are widely spoken. It is sometimes also used to refer to those Indian states whose official language is Hindi and have a Hindi-speaking majority, namely Bihar, Chandigarh, Chhattisgarh, Delhi, Haryana, Himachal Pradesh, Jharkhand, Madhya Pradesh, Rajasthan, Uttarakhand and Uttar Pradesh.
Hindi, in the broad sense, is that part of the Indo-Aryan dialect continuum that lies within the cultural Hindi Belt in the northern plains of India. In the words of Masica (1991), these [languages] are the so-called regional languages of the Hindi area, sometimes less accurately called Hindi "dialects". Hindi in this broad sense is an ethnic rather than a linguistic concept.
This broad definition of Hindi is one of the ones used in the Indian census, and results in a clear majority of Indians being reported to be speakers of Hindi, though Hindi-area respondents vary as to whether they call their language Hindi or use a local language name. As defined in the 1991 census, Hindi has a broad and a narrow sense. The name "Hindi" is thus ambiguous.
The broad sense covers a number of Central, East-Central, Eastern, and Northern Zone languages, including the Bihari languages except Maithili, all the Rajasthani languages, and the Pahari languages except Dogri and Nepali. This is an area bounded on the northwest by Punjabi, on the west by Sindhi, on the south by Gujarati, Marathi and Odia; on the east by Maithili and Bengali; and on the north by Nepali. Linguistically, the varieties of this area can be considered separate languages rather than dialects of a single language.