I have heard it said (see here, for example) that while memorial prayers for the departed are of greater antiquity, the actual text of the "El Male Rachamim" (אל מלא רחמים) originated as a response to the First Crusade and to the destruction of the Jewish communities of the Rhineland.
Where was the El Male Rachamim first printed? (The Wikipedia article to which I linked above cites a late 17th century text, but I would think that its first attestation would have been half a millennium earlier). What was the 'original' nusach? Did it involve mentioning the names of the departed, or merely referring to them as a community?