Punjab , historically known as Panchanada or Pentapotamia, is a state in northern India. Forming part of the larger Punjab region of the Indian subcontinent, the state is bordered by the Indian states of Himachal Pradesh to the north and northeast, Haryana to the south and southeast, and Rajasthan to the southwest; by the Indian union territories of Chandigarh to the east and Jammu and Kashmir to the north. It shares an international border with Punjab, a province of Pakistan to the west. The state covers an area of 50,362 square kilometres , which is 1.53% of India's total geographical area, making it the 19th-largest Indian state by area out of 28 Indian states . With over 27 million inhabitants, Punjab is the 16th-largest Indian state by population, comprising 23 districts. Punjabi, written in the Gurmukhi script, is the most widely spoken and the official language of the state. The main ethnic group are the Punjabis, with Sikhs and Hindus forming the dominant religious groups. The state capital is Chandigarh, a union territory and also the capital of the neighbouring state of Haryana. Three tributaries of the Indus, viz., Sutlej, Beas, and Ravi, flow through Punjab.