Um, if by “half a millennium” you mean five hundred years, then considering that the traditional founding event of Islam (the Hijra) happened in 622 AD/CE, you’re off by nearly 900 years, which is kind of a long error bar. Maybe you meant “a millennium and a half”?
Jeepers, you did mean “half a millennium”. I’m scratching my head on this one, Really Bright; were you by any chance violating the “don’t post after three absinthes” rule?