this is an historical aspect that completely fails in RFC.
3 of the 4 Khanates of the Mongolian Empire adopted Islam as state religion and the 4th (with core in modern day Monoglia) Buddhism. Today, Mongolians are vastly Buddhist. None of these 2 religions usually spreads to Mongolia though, incidentally making Arabia and Khmer UHV's quite hard or historically inaccurate (with strategies that include converting for example south american civs). I think something could be done to improve this side of the mod; ideas, critiques ?

In my games buddhism usually spreads in Mongolia

I've seen them Buddhist occasionally, but never Islam.

Arabia should start out with more islamic missionaries. And then, mongolia should be more willing to open borders with arabia. Part of the problem is that the mongols never really journey towards where persia is, thus limiting contact between them and arabia.

If the is a way to make buddhism and Islam more tolerent to each other, this could avoid a large negative hit from religions and make it more possible?

If the is a way to make buddhism and Islam more tolerent to each other, this could avoid a large negative hit from religions and make it more possible?

The problem with that is that historically Muslim conquerors persecuted Buddhists in north India and Bactria and Ferghana. Buddhists were a majority in Bactria and Ferghana before the Muslim conquest and had a substantial presence in north India, but Muslim conquerors destroyed almost all of the Buddhist temples and looted them (sensing, perhaps, that Hinduism was more strongly ingrained and therefore not a wise target). Today, the few Buddhists left in India live in the far south, and Buddhism has been eliminated in central Asia.