"early document" is correct and usable in written English.
For example, you could use it in a sentence like "This early document from the 18th century provides valuable insight into the events of that time period."
"Robinson Crusoe" was the great early document of radical individualism, the story of an ordinary person's practical and psychic survival in profound isolation.
"The Guardian is committed to developing content that exploits the new medium's strengths rather than simply recycling its print product," declared one portentous early document.
The other early document, unearthed in the Milanese archives about ten years ago by Janice Shell and Grazioso Sironi, seems to strengthen the case for Vasari's Lisa.
These certainly were not the souls of the married pair, as is clear both from their names and from the fact that in no early document is there mention of the genius or iuno of a dead person.
But if we are interested in what an early document like Magna Carta or a Shakespeare First Folio really means, it is vital to place it among other like objects to know how it was created, used and valued.
Now Jamal bin Huwareib, managing director of the UAE's Mohammed bin Rashid Al Maktoum Foundation for Islamic studies, has suggested that such an early document could only have been commissioned by a very small number of people – the most likely of them being Abu Bakr.
The emphasis in the first issues is given and the import of the decisions made in these early documents presented.
Early documents of the new country emphasized strong religious commitment: for example, the Declaration of Independence and Washington's Inaugural Address.
The compilers of these and other early documents had at their disposal not only oral tradition but also documentary sources.
Biblical scripture and other early documents refer to droughts, floods, periods of severe cold, and other climatic events.
Among the early documents are several letters from early 14th-century kings, granting land ownership to chief rabbis of various communities.
