Goodreads Librarians Group discussion

What should the “original publication date” be when really old works are published again in a new way. For instance these two books:
Songs of Kabir

Five t'Ang Poets
A collection of five different poets
Wang Wei - 699 to 759
Li Bai - 701 to 762
Du Fu - 712 to 770
Li Ho - 790 to 816
Li Shang-yin - 813 to 859

The date the last of the included parts was originally published would be the original publication date. You may need to estimate in this case, if the actual dates of publication (as opposed to the dates during which they wrote) is unknown.