This article offers an introductory overview of the attribution and dating of the versions of the extended Heart Sutra preserved in the Chinese Tripiṭaka and some preliminary assessment of the reliability of these sources. It includes some observations about the interesting features of each version and a stemma showing how they relate to the wider world of Heart Sutra versions. Finally, a conjecture is made about the language in which the extension was made. The Heart Sutra appears to have been extended twice in the early eighth century, leaving us with two different versions of the extended text. It appears that the first extended text, like the standard Heart Sutra, may have been composed in Chinese, while the second extended text appears to have been composed in Sanskrit.