The first conclusion to be drawn from the foregoing analysis is that ecology was a major factor determining the progress and character of the Islamic… - André Wink

We have argued that, in contrast to Iran and China, in al-Hind such a merger of the frontier world of nomadic mobility and long- distance trade on the one hand and settled agriculture on the other did occur in the eleventh to thirteenth centuries. Secondly, that this merger brought about a new productive and mercantile dynamism (without any serious deleterious impact on population density), the effects of which deepened and broadened in the subsequent centuries. This is not to deny that the Muslim- Turkish conquest of Hind was quite violent at times, and could be disruptive in some areas as well. It has not been our intention to 'sanitize' the narrative of Hindu-Muslim encounter in these centuries of invasion and extensive raiding. Nor has it been our intention to deny that in many respects the Muslim conquest was a major challenge to the integrity of Indian culture. But the Turkish-led Muslim armies that conquered North India in the eleventh to thirteenth centuries were generally small compared to those of the Mongols operating elsewhere in Eurasia; nor did a vast influx of nomads follow in their wake, unlike in Iran or parts of China.

It is a fact of immense significance that whereas in the making of Europe the conquests of Islam played the role of a powerfully effective but mostly external factor, in the East the expansion of Islam went on for more than a millennium and here, in South and large parts of Southeast Asia the association with Islam became so intimate that, as a result, we find an Indo-Islamic pattern of society and culture. (Introduction)

It is in this direction, probably, that we have to look for an answer to the question why Buddhism disappeared, in the eleventh to thirteenth centuries, from its homeland in the South-Asian subcontinent, while being successfully disseminated to the peasant societies of mainland Southeast Asia. When one turns to the secondary literature on Buddhism one finds mere hints of an explanation of this issue. If it is addressed somewhat more systematically, it usually amounts to one or another version of the theory that since Buddhism at one time prevailed only in those areas which later converted to Islam, and since there are no Buddhists left in these areas, we must deduce that the Buddhists converted to Islam. Thus it is most often observed that Buddhism disappeared from those parts of South and Southeast Asia which were overrun by Muslim armies in the medieval period and hence-forward became subject to Islamic rule. Mass conversion of Buddhists to Islam in Sind and Bengal, it is then alleged, occurred due to political pressure or because Buddhists saw in Islam a means to escape from the Hindu caste system and brahmanical oppression. This, we are told, is also the reason why Buddhism survived in areas which did not suffer the largely 'destructive' Islamic impact: the Himalayas and beyond, Sri Lanka, mainland Southeast Asia (but not Indonesia, which was conquered by indigenous Islamic rulers).