Kamboja was believed to have composed of parts that were o the either side of the Hindukush. Whereas originally they were located somewhere else. The Kamboja Mahajanapada of the Buddhist traditions refers to the 'cis-Hindukush branch' of ancient Kambojas. The kamboja being one of the sixteen mahajanapadas were a republic since ages. There are many evidence from the Mahabharata, Kautiliya's Arthashastra and Ashoka's Edict No. XIII which affirms that the Kambojas were a republic people.
Magadha emerged as a very powerful mahajanapada with time and this marked the annexation of several janapadas of the 'Majjhimadesa'. The Kasis, Kurus, Panchalas, Vatsyas etc were certainly among the exterminated clans which had no trace in the folklore, poetry and so on. The sixteen Mahajanapadas were infact distinguished as the ones belonging to the Majjhimadesa or mid India, or Uttarpatha or the north-west region.