Malwa, Doaab and Majha
Punjab state is divided into three major regions Majha, Malwa and Doaba. This division of Punjab is basically due to the rivers Sutlej and Beas flowing through the land of Punjab. In the historical times, it was not easy to cross the rivers and hence the areas divided by rivers were considered as separate regions. The regions were often ruled by different rulers or kings. The interaction between the people living in these geographically separated areas was limited. Due to this, there is a difference between the language and culture of the people living in these regions.
Note that the regions Malwa, Majha and Doaba span over the parts of historic Punjab region which includes today's Punjab (India), Haryana, Himachal Prades and Punjab (Pakistan).
Majha Between Ravi and Beas
Malwa South of Sutlej
Doaba Between Sutlej and Beas