A.A. checks out what he said in his post about India. I was curious and did google search and this is what I found. Please read it all.
In his book "Negation in India" Famous Belgian historian Koenraad Elst wrote:
The Blitzkrieg of the Muslim armies in the first decades after the birth of their religion had such enduring results precisely because the Pagan populations in West- and Central-Asia had no choice (except death) but to convert. Whatever the converts' own resentment, their children grew up as Muslims and gradually identified with this religion. Within a few generations the initial resistance against these forcible converions was forgotten, and these areas became heidenfrei (free from Pagans, cfr. judenfrei).
The Muslim conquests, down to the 16th century, were for the Hindus a pure struggle of life and death. Entire cities were burnt down and the populations massacred, with hundreds of thousands killed in every campaign, and similar numbers deported as slaves. Every new invader made (often literally) his hills of Hindus skulls. Thus, the conquest of Afghanistan in the year 1000 was followed by the annihilation of the Hindu population; the region is still called the Hindu Kush, i.e. Hindu slaughter. The Bahmani sultans (1347-1480) in central India made it a rule to kill 100,000 captives in a single day, and many more on other occasions. The conquest of the Vijayanagar empire in 1564 left the capital plus large areas of Karnataka depopulated. And so on.
According to some calculations, the Indian (subcontinent) population decreased by 80 million between 1000 (conquest of Afghanistan) and 1525 (end of Delhi Sultanate).
But the Indian Pagans were far too numerous and never fully surrendered. Against these rebellious Pagans the Muslim rulers preferred to avoid total confrontation, and to accept the compromise which the (in India dominant) Hanifite school of Islamic law made possible.
Alone among the four Islamic law schools, the school of Hanifa gave Muslim rulers the right not to offer the Pagans the sole choice between death and conversion, but to allow them toleration as zimmis (protected ones) living under 20 humiliating conditions, and to collect the jizya (toleration tax) from them.
Normally the zimmi status was only open to Jews and Christians (and even that concession was condemned by jurists of the Hanbalite school like lbn Taymiya), which explains why these communities have survived in Muslim countries while most other religions have not. Akbar (whom orthodox Muslims consider an apostate) cancelled these humiliating conditions and the jizya tax.
It is because of Hanifite law that many Muslim rulers in India considered themselves exempted from the duty to continue the genocide on the Hindus (self-exemption for which they were persistently reprimanded by their mullahs). Moreover, the Turkish and Afghan invaders also fought each other, so they often had to ally themselves with accursed unbelievers against fellow Muslims. After the conquests, Islamic occupation gradually lost its character of a total campaign to destroy the Pagans.
Many Muslim rulers preferred to enjoy the revenue from stable and prosperous kingdoms, and were content to extract the jizya tax, and to limit their conversion effort to material incentives and support to the missionary campaigns of sufis and mullahs (in fact, for less zealous rulers, the jizya was an incentive to discourage conversions, as these would mean a loss of revenue).