Punjab (/pʌnˈdʒɑːb/; Punjabi, Urdu: پنجاب, pronounced [pənˈdʒɑːb]) is one of the four provinces of Pakistan. Located in central-eastern region of the country, 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 and Autonomous Territory of AJK to the north. It shares an 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 its four major tributaries Ravi, Jhelum, Chenab and Sutlej flow through it. The province forms the bulk of the transnational Punjab region, now divided among Pakistan and India. The provincial 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 Paleolithic Soanian culture initially developed in the Soan valley. 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 main centre of Gandhara civilization. It is the site of what is considered by many scholars to be the oldest university in the world. In 326 BCE, Alexander the Great defeated the king Porus in the Battle of the Hydaspes near Mong. He also conquered Multan, an ancient centre of the Punjab region after a fierce battle.[[[Wikipedia:Citing_sources|page needed]]]_11-0" class="reference"> Subsequently, Punjab became part of the Maurya Empire, the Kushan Empire, and the Gupta Empire. In the 7th century, the region saw its first wave of Muslim conquests, which introduced Islam.[[[Wikipedia:Citing_sources|page needed]]]_11-1" class="reference"> The Umayyad Caliphate and its successor states ruled the portions of Punjab region for next 3 centuries with their capital in Multan.[[[Wikipedia:Citing_sources|page needed]]]_11-2" class="reference"> In the subsequent centuries, the region was ruled by various dynasties, including the Hindu Shahis, the Ghaznavids, the Ghurids, the Delhi Sultanate, and most notably, the Mughal Empire. In the 18th century, an invasion of Mughal Empire under the ruler Nader Shah caused Mughal authority in Punjab to collapse. Later, the region was conquered by Ahmad Shah Durrani; the founder of the Durrani Empire. It eventually lost control of Punjab as a result of the Afghan–Sikh Wars and in 1799, the Sikh Empire was formally established under the rule of Ranjit Singh with its capital based in Lahore, and Punjab remained under Sikh rule until the conquest by the British Empire in 1849. The region was central to the independence movements of Pakistan and India, with Lahore being the site of both the Declaration of Indian Independence as well as the Lahore Resolution that called for the establishment of a separate state for Indian Muslims. The modern-day Pakistani province has its roots in the Punjab Province of British India, which was divided along religious boundaries by the Radcliffe Line during the partition of India in 1947. Punjab is Pakistan's most industrialized province, with the industrial sector comprising 24 percent of the province's gross domestic product. It is known across Pakistan for its relative prosperity, and has the lowest rate of poverty among all Pakistani provinces. However, a clear divide is present between the northern and southern portions of the province; with poverty rates in northern Punjab being among the lowest in Pakistan, while some in southern Punjab are among the most impoverished. Punjab is also one of the most urbanized regions of South Asia, with approximately 40 percent of its population being concentrated in urban areas. It has been strongly influenced by Sufism, with numerous Sufi shrines spread across the province, attracting millions of devotees annually. Guru Nanak, the founder of Sikhism, was born in the town of Nankana Sahib, near Lahore. Punjab is also the site of the Katas Raj Temples, which feature prominently in Hindu mythology. Several of the World Heritage Sites listed by UNESCO are located in Punjab, including the Shalimar Gardens, the Lahore Fort, the archaeological excavations at Taxila, and the Rohtas Fort, among others.