Length of books in ancient history

Feb 2019
I am amazed it's over a million words, all researched and written by one man, that really is impressive.

In a way I am surprised the Bible is that short. Regarding novels, or non-fiction books eg history, there is no length standard of course, but it seems to me that most books I see are about 100,000 words (300+ pages of 300+ words a page). Quite a few people have written more than 8 such books. Interesting.
Voltaire Biography |

According to the above article, Voltaire wrote more than 20,000 letters and more than 2,000 books and pamphlets.

Goethe should be in the same ball park but even more versatile.