What the evidence says
The evidence on documentary proof of citizenship comes from a single source tracing legal history in Burma/Myanmar and India, and it converges on one pattern: documentation requirements do not function as a neutral, self-executing test — the burden of production, the weight given to papers, and the discretion of officials all shift over time, and each shift moves against the person holding (or lacking) the documents. In post-independence Burma, the Foreigners Act of 1864 placed the burden of proof on non-taingyintha individuals to substantiate their own citizenship claims, rather than on the state to prove foreign status — a formal allocation of the evidentiary burden onto the individual. In India, the Citizenship Act was amended twice to add documentation requirements to what had been birthright citizenship: the 1985 amendment required that anyone born after July 1987 have at least one citizen parent to qualify, and the 2004 amendment added a second documentary condition, that the non-citizen parent not have been an illegal migrant at the time of birth. Both amendments increased, rather than decreased, the documentary burden placed on individuals seeking to establish citizenship by birth.
Separately from the formal rules, the evidence also describes documentation losing force in practice. In India, administrative discretion increased relative to judicial remedies, which the source describes as reducing the official "worth" of citizenship documents even as they remained key resources for the people holding them — a description of documents losing protective value without a stated formal repeal of the rules recognizing them. In Myanmar, this went further: one account describes appearance-based assessment substituting for documentary proof in a citizenship determination, with a person's citizenship "determined by a person's features and not by the papers he holds" — a case where the practice contradicted the documentation regime, rather than merely discretion softening it. Confidence in the appearance-based finding is medium on both direction and magnitude, reflecting a single account rather than an established pattern.
On the scale of exclusion this can produce, the evidence is thin: an Indian Embassy estimate placed the number of ethnic Indians in Myanmar holding no citizenship or registration documents at all at roughly 200,000 by the early 1980s, despite decades of residence. This is flagged as low confidence on both direction and magnitude, since it rests on a single embassy estimate with unstated methodology. No claim here quantifies how many people in India were excluded by the 1985 or 1987 birthright amendments, nor how enforcement of the Burma/Myanmar burden-of-proof rule varied across district magistrates — both are acknowledged gaps rather than measured outcomes.