Kaamaroopa or Kaamaroopas is the name of the Kaamaroopa province and its people too .
As was the custom in Samskritham, country names are given by the people that inhabited it and the name is always in plural.
The king of a country derives his name by the country he ruled. E.g. Paanchaala is the ruler of the country Panchaalam,
Chaidya is the ruler of the country Chedi, Maagadha was the ruler of the country Magadha etc.
Kaamaroopa provinces are mentioned many times in the epic and other puraanams. In the Ashvamedha parvas it is mentioned that Arjuna, while following his sacrificial horse reached Kaamaropa province and its capital ciry is Praagjyothisham. That was then under control of rulers of Bhagadaththa's clan. This Kaamaroopa is identified with present Assam and the surroundings.
"After praying to Naaraayana, Nara, Sarasvathi and Vyaasa, then one should read the Jayam."
DEDICATED TO MY DEAR NIECE VYSHNAVI KRISHNA