The ground between two hills is called a valley. A very small one can be called a gully.
The area in question is known as the Piedmont region, located in Virginia between the Blue Ridge Mountains and the Coastal Plain.
The name given to a chain of islands is an archipelago.
Sorry mate, but we changed the name of the city back in 1998, now the name is Chenabnager, The distance between Lahore and Chenabnager is 150 km. The distance between Lahore and Sargodha is 172 km from Lahore and the distance between Chenabnager and Sargodha is 22 km. Complements from Chino Hills, CA and Rancho Cucamonga, CA.
The name given to an area that is a flat treeless plain is a steppe.
The proper noun for neighborhood would be a specific name given to a particular neighborhood, such as "Greenwich Village" or "Beverly Hills". Proper nouns are capitalized and refer to a specific entity, distinguishing it from common nouns which refer to general categories. In this case, the proper noun would be used to identify a unique and specific neighborhood.
valley
The Ozarks
main ridge
A region with few hills or highlands is typically called a flatland or plain.
I believe that the name is Synthetic
A region that has few hills or highlands is known as a grassland. Grasslands are one of the five major biomes.
lava
Vally Mary
Infantry or ground forces
Oakland Hills is an informal name given to the neighborhoods in the eastern sides of Oakland, California. The residences found in Oakland Hills are at the cities highest elevation and are located on the Hayward Fault Zone.
Pirate Round
The hills between Christchurch City and the Port of Lyttelton are known as the Port Hills. They form one side of the crater that is Lyttelton harbour, which was formed by the eruption of a now extinct volcano.