An "ideological" school reads ancient normative texts (the Manusmriti, the Rigveda) as evidence the system was stable for millennia, while a "socioeconomic" school associated with scholars like Nicholas Dirks and Susan Bayly treats caste as an ever-evolving social reality substantially hardened into its rigid modern form by 19th-20th century British colonial census classification, the Criminal Tribes Act, and land-alienation laws.
What would resolve this A systematic historical-demographic comparison of caste rigidity and enumeration practices before and after the onset of British colonial administration, tracing whether endogamy and jati boundaries were as fixed and countable in pre-colonial sources as colonial census records later made them appear.
OpenHistorical sociology / South Asian studiesWikipedia: Caste System in India