I'm guessing all the skeletons will be a clue.

Astounding! And of course, that's assuming that it has been in use at the same rate the entire time.

It could be that for 20 years, almost no one lived there so there were very few burials, but at another point there was a war or a plague and they were burying 100 people a day.

Edit: I forgot to mention that it's actually more than that now.

The cemetery saw heavy fighting during the 2004 Battle of Najaf. It is estimated that during the Iraq War, about 200 to 250 corpses were buried there daily; however, in 2010 this number had decreased to less than 100.[5] Approximately 50,000 new bodies are interred in the cemetery annually from across the globe.[14] This figure is an increase on the approximately 20,000 bodies, primarily from Iran, that used to be interred annually in the early 20th century.[15] Most Iraqi and many Iranian Shi'ites have a relative buried in the cemetery.[16]

Sadly, Jimi and Janis are not buried there to be part of the entertainment.

Edit: On the other hand, I'm guessing they would appreciate Arabic love poetry over Me and Bobby McGee.

I've always thought of zombies as an infection of the living or recently living. Graveyards are more of an undead thing, you need necromancy to worry about they coming back to life.

Yes, space is certainly a premium in the Arabian desert.