This article aims to study the modal elements equal to b jæ d in Persian, meaning ‘ must, should, and have to’ in some West Iranian languages, including Balochi, Gerashi, Gilaki, Hawrami, Kahangi, Kurdish, Lori, Persian, Semnani, Tati and Vafsi. It also presents the semantic map of these expressions beside a categorization of these languages based on a modal element. The investigations have indicated that some of these languages (Balochi, Bamposht dialect and Hawrami, Hawraman Takht dialect) use adverbial modals to express these notions, while as least in one case (i. e. Kahangi), there are two distinctive auxiliaries which signify ‘ must, have to, and should’ . Moreover, classification of these languages, according to a semantic feature, ends in a continuum on which languages are laid next to each other, where some of them are closer to some languages and further from the others; this is against the traditional categorizations which are mostly based on morpho-syntactic features, in which a language is whether a member of a group or not. Moreover, all the targeted elements, (expect one of the modals in Kahangi, i. e. de) besides deontic (necessity and possibility) and epistemic modality (possibility type), express participant-inherent need, participant-imposed necessity and situational necessity, as types of dynamic modality.