But how did Buddhism disappear from Central Asia especially Afghanistan and from Malaysia and Indonesia?
Again, we need to look at them separately?
For example, Syria and Egypt was majority Christian which became Muslim.
These have their own stories; you just told it.
Iran was a Zoroastrian majority which became Muslim.
Same old, same old. Iran has its own story.
However, In Central Asia including Afghanistan religions like Zoroastrianism, Tengrism, Hinduism, and Shamanism were as equally popular as Buddhism.
Can we club all these together?
But how did Buddhism disappear from Central Asia especially Afghanistan and from Malaysia and Indonesia? This is a sort of controversial issue because we don’t know the proportion of Buddhism in these areas. For example, Syria and Egypt was majority Christian which became Muslim. Iran was a Zoroastrian majority which became Muslim. However, In Central Asia including Afghanistan religions like Zoroastrianism, Tengrism, Hinduism, and Shamanism were as equally popular as Buddhism. Even the center of Zoroastrianism was Balkh in Afghanistan. Same In Malaysia and Indonesia, Hinduism was as popular as Buddhism and it is difficult to estimate the proportion of Buddhists in relation to the overall population.
As a result, many scholars put different theories. Some say that lack of state support caused decline in Buddhism, some say Buddhism was weaker in these places before Islam and so it became vulnerable to Islamic conversion. What do you think?
So let's look at the neighbouring countries of Myanmar and Thailand; what happened?
First, Cambodia. It remains Buddhist, having come to it through a period of mixed Hindu-Buddhist society. One factor behind all three is the very strong common ethnic bond - a very large majority ethnic population and a single language - although Myanmar is racked by insurrections of the tribes on the fringes of the sprawling Burmese Empire that was crushed by the British at a particularly weak moment in its history.
Second, Malaysia (and Indonesia - the differences will become clear a while later). Why these two countries turned to Islam is a complicated matter. Both had the same ethnic homogeneity and the language homogeneity as the first three mentioned had, but both turned to Islam, a very moderate form of Islam in general, but verging on the stricter forms in the northern parts of Malaysia, the Malay part, and in the northern tip of Sumatra, in Aceh. However, between them, Indonesia has a form of culture and society that continues to be heavily influenced by the older Hindu-Buddhist legacy of those islands, so much so that many of their names, their proper names, are instantly recognisable by, say, an Indian.
The question is not of what they are today, but why did Buddhism fail, and give way. Could it have been the Bangladesh model, or the Kerala model, where Arab traders, and, in general, heavy trade links with the western portions of the Indian Ocean littoral brought the new religion into focus and persuaded a number of people to convert to Islam? That cannot be a reason by itself, as Cambodia was as heavily connected to trade - more, much more than Malaya (considering it separately from its modern national shape and configuration of Malaysia), although Indonesia, due to being the origin of many very valuable spices, was as heavily invested in international trade as Chittagong in Bangladesh or the Kerala coast and Calicut (Kozhikode) in general.
We may have to return to this question of Malaysia and Indonesia later.