From the longer Wikipedia page .
The Bower Manuscript is an early birch bark document, dated to the Gupta era (between the 4th and the 6th century). It is written in Buddhist Hybrid Sanskrit using the Late Brahmi script. The manuscript is notable for preserving one of the earliest treatises on Indian medicine (Ayurveda). Rudolf Hoernle (1910) suggested that the text of the manuscript contains excerpts of the (otherwise unknown) Bheda Samhita on medicine. The medical parts (I-III) constitute may be based on similar types of medical writings antedating the composition of the saṃhitās of Caraka, Suśruta, and as such rank with the earliest surviving texts on Ayurveda.
It is today preserved as part of the collections of the Bodleian Library in Oxford. The Bower Manuscript in reality is a collection of seven distinct manuscripts, or it may be called a collective manuscript of seven parts.