Punjab is one of the four provinces of Pakistan. Located in central eastern region, Punjab is the second-largest province of Pakistan by land area and the largest province by population. It shares land borders with the Pakistani provinces of Khyber Pakhtunkhwa to the north-west, Balochistan to the south-west and Sindh to the south, as well as Islamabad Capital Territory to the north-west, Autonomous Territory of AJK to the north and International border with the Indian states of Rajasthan and Punjab to the east and Indian-administered Kashmir to the north-east. Punjab is the most fertile province of the country as River Indus and it's four major tributaries Ravi, Jhelum, Chenab and Sutlej flow through it. Forming the bulk of the transnational Punjab region between Pakistan and India, it is bounded locally by Sindh to the south, Balochistan to the west, Khyber Pakhtunkhwa to the northwest, the Islamabad Capital Territory to the north, and the Pakistani-administered territory of Azad Jammu and Kashmir to the northeast. On its eastern side, it is bounded by the India–Pakistan border, sharing an international boundary with the Indian states of Punjab and Rajasthan to the east and southeast, respectively, and a disputed boundary with the Indian-administered territory of Jammu and Kashmir to the northeast. The province's capital is Lahore—a cultural, modern, historical, economic, and cosmopolitan centre of Pakistan. Other major cities include Faisalabad, Rawalpindi, Gujranwala, Multan, and Sialkot. Punjab is also the world's fifth-most populous subnational entity, and the most populous outside of China and India. Modern-day Pakistani Punjab has been inhabited since ancient times; the Indus Valley civilization, dating to 3300 BCE, was first discovered at Harappa. It features heavily in the Sanskrit-language Indian epic known as the Mahabharata, and is also home to Taxila, the site of what is considered by many scholars to be the oldest university in the world. Punjab is one of the four provinces of Pakistan. Located in central eastern region, Punjab is the second-largest province of Pakistan...Punjab, is known for its ancient cultural heritage as well as its religious diversity. The lands of Punjab have been home to a number of Sufi Shrines, Hindu Temples and holiest sites of Sikhism. The Indus Valley Civilization once ruled the region. The Gandhara civilization was also quite dominant in the northern region of Punjab at Taxila. Punjab represent a unique mixture of Mughals, Sikhs and Colonial architecture.