According to tradition, the Karkathar migrated from the Gangetic plains and over time spread over the entire macro region of present day Tamil Nadu. According to satakams, the Pandya country was settled by these people after they had resided in the Chola country. According to historian Burton Stein, this theory is purely mythical.
According to anthropologist Nicholas B. Dirks, the Pudukottai region was sparsely populated until the early Chola period. But with the beginning of the Chola era, there is strong evidence of increasing agrarian settlement, the growth of villages, institutions, the construction and expansion of temples. According to the Tekkattur manuscript, the Karkathar were initially divided into Kanāttars and Kōnāttars, each of which had many exogamous sub-divisions. Kōnādu or the land of the king (Chola country) mostly consisted of the regions north of the river Vellar except for the western part of the state where it included certain regions south of the river as well. Kanādu, literally meaning the land of the forests was included in the Pandya country. The manuscript goes on to describe the decline in the position of the Karkathar after the initial golden age due to the fighting between the two branches over various issues such as land, rights to the water of the river Vellar, temples etc. and the subsequent settlement and dominance of the Maravars in the region who were initially imported from Ramnad by both branches. The copper plate inscriptions held by every Maravar community in the region indicates that the Kōnāttu vellalar were victorious in the end.
According to historian Arokiaswami, the Irukkuvels of Kodumbalur who were the main allies of the Cholas from an early period were all Vellalars. According to Dirks, the local sources like palm leaf manuscripts, copper plate inscriptions and many of the origin stories also indicate that there was a relationship between the Irukkuvel family of chieftains and the Karkathar vellalar community and he says, that the Irukkuvel titles such as Vēlār as in Madurantaka Irukkuvēlār, Śembiyan Irukkuvēlār, etc. proves that the Irukkuvels were indeed Vellalar. Stein disputes Arokiaswami's claim that the Irukkuvels were Vellalar.