Solution:
Doab is an area, or the portion of land situated between two rivers. Punjab is divided into Three regions according to flow of rivers. These are Majha, Malwa and Doaba. The region lying between Ravi and Beas is called Majha. The line between Beas and Sutlej is called Doaba. The region lying in the South of Sutlej River is called Malwa.
The Bari Doab is located between the Beas and the Satluj. This region is also known as 'Majha', which consists of four districts namely, Pathankot, Gurdaspur, Amritsar, and Tarn Taran.
The Bist Doab is situated between the rivers Satluj and Beas. It includes the districts of Jalandhar, Kapurthala, Hoshiarpur and Shaheed Bhagat Singh Nagar.
The Suj Doab is located between the Satluj and the Yamuna. This region of the doab forms the historical Malwa region, the largest region of Punjab.