The term Punjab comprises two words: "punj meaning five and ab meaning water, thus the land of five rivers." The Greeks referred to Punjab as Pentapotamia, an inland delta of five converging rivers. In Avesta, the sacred text of Zoroastrians, the Punjab region is associated with the ancient hapta h?ndu or Sapta Sindhu, the Land of Seven Rivers. Historically, the Punjab region has been the gateway to the Indian Subcontinent for most foreign invaders.
Agriculture is the largest industry in Punjab. Other major industries include the manufacturing of scientific instruments, agricultural goods, electrical goods, financial services, machine tools, textiles, sewing machines, sports goods, starch, tourism, fertilizers, bicycles, garments, and the processing of pine oil and sugar. Punjab also has the largest number of steel rolling mill plants in India, which are located in "Steel Town"—Mandi Gobindgarh in the Fatehgarh Sahib district.