Kimpurusha Kingdom refers to the territory of a tribe called Kimpurushas who were one among the Exotic Tribes of Ancient India. These exotic tribes lived in inaccessible regions like the Himalaya mountains and had limited interaction with the Vedic civilization of ancient India. Thus they were represented as super human beings or as natural spirits.
Kimpurushas were described to be Monkey-headed beings with tails like monkeys. Lord Hanumana is kimpurusha according to Bhagawatam Who burned the Lanka using his long tail. Splitting the word to Kimpurusha = Kim (Is it ? ) + Purusha (Man) (literally translated "Is it human ?"), analogous to the word Kin + Nara (Man), shows that Kinnaras and Kimpurushas were related or probably the same tribe. The lion head may be an exaggeration of their heavily bearded head. In some Purana's they were mentioned as horse-headed. They could be a tribe of horse-warriors like the Kambojas. But their lion-headed reference in the sources and them staying in the mountains suggest that they could be Kirata. Kirat-or Kirati- means people with lion nature. It is derived from two words Kira-Lion and Ti- people and it also means people from the mountain.
Kimpurushas In Ramayana
In Ramayana, Lord Rama Destroyed Rawana Kingdom Lanka With the help of vanaras and kimpurushas. Lord Krishna Says Uddhava! I'm Hanumana in all kimpurushas.