Raghuvamsa of Kalidasa
Raghuvamsa of Kalidasa (5th c AD) contains references to Kambojas and informs that, during his digavijaya expedition, after reducing the countries of Western-Ghats, king Raghu proceeds via land-route to conquer the Parasikas. The Parasikas lose the battle. Raghu's forces move in north (kauberi) direction from Parasika (Sassanian) land and hit Vamkshu (Oxus). At Vamkshu, Raghu's horses take breather and shed off the Kesra (safron) leaves from their shoulders by rolling in the sands of Vamkshu Banks. Here follows the encounter with the Hunas on west Banks of Vamkshu. The Hunas in 5th c AD were located in west parts of Oxus country i.e. in Bactria. The Huna forces meet with complete disaster. Immediately after reducing the Hunas on western bank of Oxus, Raghu faces the Kambojas, defeats them and obtains numerous expensive gifts and top-notch war horse from them as a tribute. This tradition verifies that the Kambojas were located in close neighborhood to the Hunas in eastern Oxus country, in 5th c AD.
Read more about this topic: Kambojas In Indian Literature