Commons:Upload/Unknown author or license
Wikimedia Commons has a mandate only to provide works that are known to be available under a free license or to be in the public domain— that is, works that are known not to infringe on the copyrights of any author. If we don't know who the author is and when the work was created, then we can't know the copyright status and we can't know what licenses, if any, apply to the work. There are certain exceptions, of course: if the author was never really known, if the work is too simple to qualify for copyright protection, or if the work is "old enough" (no country currently offers copyright protection to works whose author has been deceased for more than 100 years— see Commons:Copyright rules by territory), then the "author" field is not compulsory. If you are still in doubt, you are encouraged to ask for help at the Helpdesk.
Works which do not include the name of the author or which are not otherwise clearly in the public domain will be tagged for deletion. Please don't upload them to Wikimedia Commons.