A valuable prose text, Tārīkh-i Bayhaqī [Beyhaqi’s History], is a reflection of the thoughts, socio-political and spiritual beliefs of Iranians living in the fifth century. Using a descriptive-analytical method based on Jakobson’s communication theory, this study, examines the structure of sentences, types of sentences, and how they are applied, and annalyzes the important indicators of syntactic structures in Tārīkh-i Bayhaqī. It then identifies their connection with the intellectual and semantic features of Tārīkh-i Bayhaqī. The findings show that although the sentence structure in Tārīkh-i Bayhaqī often follows the common patterns of the fifth century, its prose is highly flexible and defamiliarized in the arrangement of speech components. Beyhaqi employed rhetorical methods such as topicalization, reattribution, composition, anaphora, and ellipsis, using verbs without subjects or agents, indirect commands, passive verbs, and the replacement of parallel syntactic structures, to indirectly express his thoughts. This not only embellished the speech and created unique structures but also transformed the pure and impartial narration of history into historical analysis by hinting at hidden and unspoken ideas. Ellipsis is used in most of Beyhaqi’s sentences to create complex sentences, textual cohesion, speed and rhythm in the speech, conservatism, as well as to indicate certain components as unimportant.