Egophoricity is a cross-linguistically rare grammatical phenomenon. While numerous descriptive studies have substantially improved our synchronic understanding of the category in recent years, we are still largely ignorant of the diachronic origins of egophoricity systems. In this article, we address this gap and discuss a diachronic process that transforms person agreement markers into egophoricity markers. Based on evidence from three Tibeto-Burman languages, we reconstruct the diachronic transformation and argue that the process starts out in reported speech clauses once the direct construal of the predicate is generalized. This generalization allows for the functional reanalysis of first and third person markers as egophoric and allophoric markers, while second person markers become functionally obsolete. Once person markers have undergone an epistemization in reported speech clauses, the innovative epistemic system is extended to simple declarative and interrogative clauses, where it gradually replaces the conservative person agreement system.