Based on natural conversational data, the current study analyzes utterance-final pragmatic particle lāh in Shishan, a dialect of Lingao of the Tai-Kadai language family. The research proposes that lāh signals an interactively built, relational notion of restrictivity. Specifically, lāh signals to the addressee that the state-of-affairs described in the utterance is restricted such that "nothing else" is possible due to a pre-existing, external constraint. The core meaning of relational "nothing else" gives rise to such pragmatic extensions as marking suggestions necessitated by external circumstances, assertion of "obviousness", negative politeness strategies, and various emotive stances toward the situation in focus and/or toward the addressee. The range of functions of lāh parallel a number of Southeast Asian languages' pragmatic particles (e.g. Cantonese lo, Mandarin me, Singapore English lor), particularly surrounding the function of marking the propositional content as "obvious". The overlap corroborates a recurrent theme in the expanding research on pragmatic particles, specifically, pragmatic particles' encoding the speaker's subjectivity toward the content being communicated. Equally important is that their use is prompted by, and in turn, responds to, perceived sharedness/divergence in the speaker's and addressee's subjective understandings of the world, an embodiment of the "intersubjective" nature of language.