Yeh it is kind of informative to visualise it in that way, certainly puts a broader perspective on things.
I've always found it quite a coincidence how Hinduism and Judaism both sprang forth sects that grew into much larger religions than the original, through the coming of some all-great central person who revolutionised the teachings, and this map highlights that.
Strange though that they show Judaism starting with the birth of Abraham (Pbuh), who was in fact father of the Arabs (as well as Jews), and therefore Islam, whilst Jews consider themselves to follow the religion of Moses (Pbuh) and that he was the founder of their religion. It's even stranger because Yehudah (from where we get the word Judaism) was a descendant of Abraham, did he follow the religion founded by his descendant?
I've seen similar maps before to illustrate the expansion of the Islamic Caliphate and also another to illustrate the expansions of the Western & Eastern Blocs during the Cold War. And actually recently I made a (static) map of the Islamic world to illustrate one of the Hadith (sayings) of Muhammad (Pbuh).
Quote:With PNG, do 'they' know exactly how far Islam reached?
As far as I know, Islam never ruled any part of Papua. Indonesia annexed it in the early 1960's long after Islam had ceased to exist as an empire.