Most of the extant ancient texts have at least a couple of manuscripts going back to the 11th century CE or so. Often times there are branches (with differences in the texts) which trace back to single texts in the late antique period. Usually, texts which are outside of this are either palimpsests or come from papyri. One example of a text that survived from a single manuscript is the Homeric Hymn to Demeter, which is only preserved in one manuscript, called "M." It was compiled in Constantinople in the middle to late 15th century CE, and now is located in Leiden. The lost Hymn to Dionysus was also in this manuscript at one point. link to the Hymn to Demeter.