I think, you are wrong to say that the Muslims killed Hindus when it was not a battle. After the Muslims had established themselves in Delhi and Hindustan after defeating the ruling Hindus in about 1192 AD, it was more infighting among themselves throughout the six Centuries of their rule.
These Muslims killed each other in order to establish supremacy. This was repeated time and again. Please read the contemporary history books to get an unbiased view of what really happened in those Centuries.
This view presented by Eastwatch is actually a more balanced view, rather than asserting that there was a continuous and sustained massacre of non-Muslims, or even that violent conversions continued throughout the year.
What seems to have happened was an initial period of
blood-letting. It was legal in Arabic military custom to kill combatants after their defeat in battle, although it was not so in Indian custom. Their wives and children, other dependants as well, were sold as slaves.
Subsequently, there was
sustained social pressure. While submissive and non-combatant non-Muslims were allowed to lead their own lives, subject to Muslim law, they were by all accounts humiliated at every turn by enthusiastic proselytisers: their temples were defiled, their practices mocked, their monuments and buildings taken over just to humiliate them, their children kidnapped and accusations of blasphemy and contumelious behaviour towards the Prophet and the Book were rife.
Reflections of this are to be seen even today, in Muslim majority areas of the sub-continent. Our daily newspapers in Pakistan are full of them; I have not followed Bangladeshi newspapers.
Thirdly, periodic pogroms and
extended social punishment. From time to time, on the accession of particularly violent monarchs, the entire character of administration relating to non-Muslims would take a turn for the worse. These campaigns were sometimes related to issues, sometimes not. At times, they were subject not to punishment by the state, but to punishment by civilians, other enthusiastic Muslims acting on their own initiative.
The sum total was a determined drift towards conversion. It is clear that not all of it occurred due to force. It is equally clear that over and above the fear of imminent death, there was pressure of other kinds, many intolerable. And the effects of
the wise teachings of the Sufi saints, the voluntary conversions of the West Coast and of Karnataka, of Bengal above all, are not to be ignored.