Here's an interesting one. Not quite in the 300,000 class but I reckon the earliest we have so far.
The Good Book, I Samuel, 18,6-7.
Thewomen come in playing tabrets(bodhrans?) and musical instruments(note the distiction) and proceed to sing"Saul has slain his thousands, and David his ten thousands". Not bad eh? which leads me to a new category
MOST HOMICIDAL SINGER/SONG WRITER
Leadbelly murdered two people, Henry VIII got rid of a few wives(and Thomas More) while writing Greensleeves, and some of these rap chappies are apparently a bit violent. But King David(who, in case you've forgotten, wrote the Psalms)..ten thousands eh? Got to be the prime contender.