Books have been translated for thousands of years, with no central record of the fact.
In 1946, the United Nations superseded the League and UNESCO was assigned the Index.
So, for example, while the Bible is the single most translated book in the world, it does not rank in the top ten of the index.
Hence, the top authors, as the Index presents them, are from a database query whose results require interpretation.
According to the Index, Agatha Christie remains the most-translated individual author.