The earliest reference of Karikaala's conquests to countries beyond tamilagam appears in pattinappalai. Here, katiyaloor uruthirankannanar says that "among those subjucated by karikaala are Ozhiyar, ancient aruvaalar, NORTHERERS, WESTERNERS and pandiyas". Not sure if these lines were written under the influence of any liquor
Ahananooru, puram, patthuppatu (porunar aatruppadai) all sing in praise of various exploits of karikaala.
Then comes silappathikaaram. It very clearly says that (V 90- 104): King thirumaavalavan, eager for war AND FOUND NO MATCH IN TAMIL LAND UNDERTOOK AN EXPETITION AS FAR AS HIMALAYAS AND OBTAINED GIFTS FROM KINGS OF MAGADA, VAJRA AND AVANTHI COUNTRIES. Here we certainly have to trust the strict discipline meant for saints in those days and hopefully Ilangovadigal was not under any negative influence.
Adiyaarkunallar's commentry on silappathikaram quotes a stray venba wherein karikala is said to have used a sendu (Given to him by sattan a guardian deity) to go round the himalayas
Manimekalai: (1.39)"As on the day when karikala went forth..." mentioning his northern campaign
All the chola copperplates celebrate karikala's general exploits
Kalingathupparani (V1-4): Karikala is said to have subdued himalayas.
Ottakkothar's vikrama chozhan ula as well as rajaraja chozhan ula celebrating himalayan victory
The chinese traveller account of cholas (as quoted by K.A.Nilakanda sastri) also calls cholas as CHOULEAN.
It is with this historic setting in background that Historian Ira Iragavaiyangar should have remarked about the pass.