The study humans prior to the invention of writing WordNet 3.0

The study of humans prior to the invention of writing Open English WordNet

Protohistory is the period between prehistory and written history, during which a culture or civilization has not yet developed writing, but other cultures that have developed writing have noted the existence of those pre-literate groups in their own writings. Wikipedia

A period between prehistory and history, during which a culture or civilization has not yet developed writing, but other cultures mention it in their writings. OmegaWiki

The period between prehistory and history, during which a culture or civilization has not yet developed writing, but other cultures have already noted its existence in their own writings. Wiktionary