This study is an attempt to ascertain the geographical position of Punyāt Ardashir, the Sasanid stronghold in North-Eastern Arabia, identifiable with Madīnat al-Khaṭṭ of al-Ṭabarī’s history. To do that, it is necessary to understand, what the names al-Khaṭṭ and Madīnat al-Khaṭṭ applied to. In mediaeval Islamic literature the name al-Khaṭṭ had different meanings and was used to denote a settlement in the region then called al-Baḥrayn and embracing the territory from Basra to Oman, an island in the Persian Gulf, and the coastal zone of the region of Baḥrayn. The word ‘madīna’ denoted a town when preceding the town’s name, and a capital when followed by the name of the region. Therefore, it should not be assumed that Madīnat al-Khaṭṭ meant ‘the town of al-Khaṭṭ’. The lack of references to Madīnat al-Khaṭṭ in the extant sources, including when such references would be expected, suggests that Madīnat al-Khaṭṭ was the capital of the region of al-Khaṭṭ, which had a distinct name. That regional capital is not necessarily identical with the settlement of al-Khaṭṭ. This means that the only firm basis for any tentative localization of Madīnat al-Khaṭṭ is its status of the regional capital. Madīnal al-Khaṭṭ is to be expected to have been the residence of the Sasanid marzbān, and to have been sharply defended by Persians during the Islamic conquest. The place which best fits to that description appears to be the fortress of al-Zāra situated in the territory of present-day al-Ḳaṭīf. Therefore, Madīnat al-Khaṭṭ is probably identical with al-Zāra.