Parama Kamboja Kingdom was mentioned in the epic Mahabharata to be on the far north west along with the Bahlika, Uttara Madra and Uttara Kuru countries. It was located in parts of modern-day Afghanistan, Tajikistan and Uzbekistan.
Parama Kambojas in Kurukshetra War
Drona Parava of Mahabharata refers to 6000 soldiers from the Parama Kamboja group who had sided with the Pandavas against the Kauravas in the Kurukshetra war. They have been described as "very handsome, very fortunate Kambojas" (prabhadrakastu Kambojah), extremely fierce, 'Personification of Death' (samanmrityo), fearful like Yama, the god of death and rich like Kuber i.e. god of treasure (Kambojah.... Yama. vaishravan.opamah: 7.23.42-44).
References
Parama Kamboja Kingdom Wikipedia(Text) CC BY-SA