Punjab (; ; ; ; also romanised as Panjāb or Panj-Āb) is a geopolitical, cultural, and historical region in South Asia, specifically in the northern part of the Indian subcontinent, on the Indus Plain comprising areas of eastern Pakistan and northwestern India. Punjab's major cities are Lahore, Faisalabad, Rawalpindi, Gujranwala, Multan, Ludhiana, Amritsar, Sialkot, Chandigarh, Shimla, Jalandhar, Gurugram, and Bahawalpur. Punjab grew out of the settlements along the five rivers, which served as an important route to the Near East as early as the ancient Indus Valley civilization, dating back to 3000 BCE, and had numerous migrations by the Indo-Aryan peoples. Agriculture has been the major economic feature of the Punjab and has therefore formed the foundation of Punjabi culture, with one's social status being determined by land ownership. The Punjab emerged as an important agricultural region, especially following the Green Revolution during the mid-1960s to the mid-1970s, and has been described as the "breadbasket of both India and Pakistan." The Punjab is accredited for its colourful history in terms of its native dynasties and empires. Following Alexander the Great's invasion and his conflicts with Porus and the Malli tribe of Multan, Chandragupta allied with various Punjabi tribes to defeat Dhana Nanda and form the Mauryan empire After its decline the Indo-Greeks, Kushan Empire and Indo-Scythians successively established kingdoms in Punjab however they were defeated by various Eastern Punjab republics (c. 4th BCE - 4th CE) who previously established the Mauryan empire. These include the Yaudheyas, Trigartas, Audumbaras, Arjunayanas and Kunindas in which the victories can be confirmed through their coinage.The devastating Hunnic invasions of Punjab occurred in the 5th and 6th CE however they were ultimately defeated by the Vardhana dynasty (originally based in Eastern Punjab) which proceeded to rule over Northern India for the next century. Most of the Western Punjab region became unified under the Taank kingdom, established in the 6th century, however little is known about this kingdom due to the lack of historical description. In the 8th century it was replaced with the Hindu Shahis, their roots described as Punjabi Brahmins and accredited for the defeat of the Saffarid dynasty and Samanid Empire. In the same period, between the 8th and 12th century, the Tomara dynasty and Katoch dynasty controlled the eastern Punjab region and resisted many invasion attempts from the Ghaznavids. Islam became established in Western Punjab under the Ghaznavids, after whom the Delhi