This volume contains editions of a series of Tantric texts in Old Uyghur in the Berlin Turfan Collection. This volume contains an edition of a corpus of Old Uyghur Tantric texts which is usually called Aparimitāyus-Literature, mainly consisting of two texts, the Ārya-aparimitāyur-jñāna-nāma-mahāyāna-sūtra and the Amṛtadundubhisvaradhāraṇī. The first one is one of the longest Tantric texts in Old Uyghur and was widely disseminated in medieval Central Asia via translations into various languages – Chinese, Khotanese, Mongolian and Tangut. In addition to these, this volume also includes an edition of some hitherto-unknown important Tantric texts in Old Uyghur, such as the Vajrasattva-mantra, a description of Tejo-Mahākāla and the Vajravidāraṇā-nāma-dhāraṇīsādhana. These texts are crucial to a comprehensive understanding of Old Turkic language and Central Asian Buddhism, particularly in their contribution to our knowledge on aspects of late Old Uyghur and Uyghur Tantric Buddhism in Turfan and Dunhuang between the 13th and 14th centuries. All these texts are provided with an introduction, transcription, transliteration, translation and a detailed commentary, and the volume concludes with a glossary and four plates.