After re-reading my post, I realized there is nothing like promotion/expansion in Hinduism. I've read that you cannot convert to a Hindu. You are either born a Hindu or not.
Herez an embedded flash animation taken from mapsofwar about the history of religion. An interesting 90 sec watch. Looking at the map and my own knowledge, I felt Islam and Christianity were well organized and advertized? to gain the popularity across the world, in the recent past. Hinduism does not have missionaries as aggressive as christianity to promote its religion. Not that I am FOR organized religion.
I feel it (organized religion) should not be treated any differently than a political party with an agenda. Religious institutions should not be tax exempt. I believe they would not become such huge institutions atleast in USA if its not for the tax exempt status.
Anyways, its interesting to see that hinduism is the oldest of all religions (atleast from this animation)