Re: reusing the same site for burial
What are you guys talking about? 100 years? 200 years?
What I have seen in Janaat-al-Baqee (in Medina), one of the most famous Islamic graveyards, is that graves are leveled out after SIX MONTHS and reused. If you walk in there, you can actually see skeletons (khopris, bones, arms) visible from many graves.