‘No one asked your opinion, you filthy little Mudblood,’ [Draco] spat.
Chamber of Secrets - page 86 - Bloomsbury - chapter 7, Mudbloods and Murmurs
‘It’s about the most insulting thing he could think of,’ gasped Ron, coming back up. ‘Mudblood’s a really foul name for someone who was Muggle-born – you know, non-magic parents. [...] It’s a disgusting thing to call someone [...] Dirty blood, see. Common blood. It’s mad. Most wizards these days are half-blood anyway. If we hadn’t married Muggles we’d’ve died out.’
Chamber of Secrets - page 89 - Bloomsbury - chapter 7, Mudbloods and Murmurs
Why do purebloods call Muggleborns 'Mudblood'? When and how did this pejorative start?
I'm already aware of J.K. Rowling's parallel themes of Voldemort purging the Muggleborn and Half-bloods wizards and witches and the genocide of Nazi Germany¹ and that's not the topic I'm looking for an answer from. If it's relevant to your answer in a couple of places, though, that's fine. What I'm asking here is whether or not there is a history behind the word 'Mudblood', and, if so, what is it? Or is 'Mudblood' a more recent term, perhaps having come in style in the 20th century? As well, I'm already aware that 'Mudblood' means 'dirty blood'.
★ I'm looking for a canon-based answer (the Harry Potter Novels, the three supplemental books, JKR interviews, and Pottermore) and do not prefer an answer from the HP Wikia or the Wikipedia.
¹Obligatory Godwin nod.