This is a really good 90 second map of the birth and spread of religions:

http://www.mapsofwar.com/ind/history-of-religion.html

Several points of interest:

* The mother of the great cultivation techniques in the world is definitely India. As to Egypt/Babylonia and Assyria,  and the Aztec/Mayan civilizations, nothing much is left to tell us of their techniques and traditions. All civilizations die out in time due to lack of merit or in socio-political terms, the civilization just ran its course. Same for peoples, same for nations … religions are no different (witness Zorasterism). Plenty of spiritual techniques and philosophies were developed in India, many of which have been duplicated in European traditions with their Indian (or even Tibetan) first origins ignored. Perhaps due to the feng shui of the region (its chi) or some other reason, this is where the great cultivation masters sprout up time and time again … most great masters in ancient times went EAST and East meant India or Asia for training purposes. WHo knows where Jesus went during his lost years?

* Buddhism originated on top of these Indian systems and picked from the very best for its teaching structure. It appealed only to the highest levels of educated society and had to be robust to stand their scrutiny as well as really be a guiding path through the countless India competing schools and dogmas. In time, it died out in India due to public preference for ceremonies and the unwillingness to buy into personal responsibility for liberation cultivation, etc. and grafted itself onto China, and  the rest of Asia. China had developed its own set of independent but similar spiritual traditions, so was able to use Buddhist principles to enhance them. As my teacher often says, the great Buddhas when they want to be born are born into poor countries where there is a LARGE population, not small countries like Tibet where their influence would be minimal. China and India fit these qualifications.

* Islam originated in poor, waterless desert kingdoms where the living is not the easiest. Due to the corresponding lack of merit  within the populace (otherwise you’re not born into such poor regions lacking any cultivationculture as well), the main method of Mohammed was to instruct merit making and cultivation through disciplined prayer cultivation several times a day. Discipline + cultivation build up the merit of a people over time - witness Japan’s economic resurgence this century due to national sacrifice and discipline. It’s interesting that Islam spread through a method similar to the Bodhisattva Manjushri: "I have a book of laws and a sword. Follow the one or you get the other." This was the way to graft a civilizing influence onto the people and create a great and noble civilization in time that might never have developed otherwise. It’s imposed onthem, otherwise it would never take hold. Expedient means for the situation at hand, but certainly not for today.

* Christianity’s spread was sporadic and diffuse at first, mostly due to missionary influences rather than the logic of stream itself, and its origins actually concentrated on people considered the lowest levels in society. Without the influence of St. Paul, who had practically no cultivation accomplishments but just an intellect, it was turned into a religion. Missionary work, rather than excellence of the logic of the tradition or robustness of its cultivation methods, is still the main way it grows today.  It thrives primarily in rich countries, which is akin to saying nations with lots of merit. Incidentally, it emphasizes charity, good works and offering which have corresponding karmic returns, and there is this tie-in as to why  many rich countries (not all) have a Christian bias.

All of these religions grow over time, spread and will die over time. All of them. Nothing is permananet. New masters will arise with expedient teachings for a time. Some will take hold and some won’t. Some will spread, some won’t. It’s really that simple. The crux is to find cultivation teachings within a tradition and hold to those for your own personal development. As to external dogmas, many are created, warped, twisted, etc. for political expediency and to rule populations rather than being commandments of religion or eternal laws of universe. But ignorant people don’t know that, and even if you do, one must fit in to the status quo or risk life, limb, wealth, reputation and so forth. It’s as simple as that.