The Amaraughaprabodha is a Śaiva work on yoga that is attributed to Gorakṣanātha, the founder of the Nath Sect and a pioneer of a physical type of yoga called Haṭhayoga, some techniques of which are still practised in many forms of modern transnational yoga. An edition of this work, based on one manuscript, was published by Kalyani Mallik in 1954. In this talk, I will present new manuscript evidence which indicates that the Amaraughaprabodha was probably one of the earliest texts to teach Haṭhayoga. It is also evident that the author of the Amaraughaprabodha created Haṭhayoga from the yoga of the Amṛtasiddhi, which is a Vajrayāna work composed sometime before the mid-twelfth century. By examining the shared content between the Amṛtasiddhi and the Amaraughaprabodha, I will discuss how the Buddhist yoga of the former was adapted for Śaivas and how the ‘force’ of Haṭhayoga was conceived in the Amaraughaprabodha. I will conclude with some general observations on the emergence of Haṭhayoga from the tantric traditions that preceded it and the transformation of Haṭhayoga from an auxiliary practice, as it is taught in the Amaraughaprabodha, to a complete system of yoga that was appropriated by Brahmanical traditions from the sixteenth century onwards.