The Ningthouja dynasty is considered the primary ruling power of Manipur during the medieval period. It was based in:

The correct answer is: a) The Imphal Valley.

The Ningthouja dynasty was a royal dynasty that ruled the Meitei people of Manipur from the 14th century to the 20th century. The dynasty was founded by Nongda Lairen Pakhangba, who is considered the first king of Manipur. The Ningthouja dynasty was based in the Imphal Valley, which is the central and most populous part of Manipur. The dynasty was known for its military prowess and its contributions to Manipuri culture.

The Ukhrul Hills are a mountain range in the north-eastern part of Manipur. The Kabaw Valley is a valley in the south-eastern part of Manipur. The Churachandpur Hills are a mountain range in the south-western part of Manipur. None of these places were the primary base of the Ningthouja dynasty.