Answer : 1. "Mahi Basin"
Explanation :

1. Central Mahi Basin is connected to “Chhappan Plain”. Between Banswara and Pratapgarh, an area known as Chhappan Plains is formed by the Mahi River and its tributaries. It includes 56 villages. The Chhappan region is deeply and complexly incised resulting in the formation of isolated hills, not dissimilar to the Mewar plain to the north. This deeply dissected area is locally known as ‘Bagar’ and includes the hilly areas of Banswara and Dungarpur.

2. The plain formed by the Mahi River and its tributaries in the southern part of the Banswara and Pratapgarh districts of Rajasthan is called the Mahi Plain. A group of fifty-six villages and fifty-six rivers and streams are situated in this plain, it is called the Plain of Chhappan.

Specialty of Chhappan Ka Maidan

1. Chhappan ka Maidan is also called Madhya Mahi Maidan.

2. This plain is an area of barren valleys.

3. It is spread over some parts of Dungarpur, Banswara, Pratapgarh and Udaipur and its flow also towards the Arabian Sea.

6. This plain is divided into three parts, namely Chambal Basin, Banas Basin and Central Mahi Basin.

7. Chhappan village group is situated in the area between Pratapgarh and Banswara, hence this area is also known as Chhappan Plain.