This paper examines the evolution of two separate but interrelated aspects of the grammar of Sinhala: the distribution of the Question-particle da and the formation of relatives clauses in the history of Sinhala. I also examine the structure of relative clauses and the distribution of Question-particles in genetically-unrelated but geographically-proximate Dravidian. The possible role of language contact in the evolution of certain Sinhala grammatical structures—including the employment of the particle da—which have no parallels in other Indo-Aryan languages—is also considered.