here's the section from that link:
The unsuccessful Muslim attack on Nepal and Tibet
Less is known of the Muslim attack on Nepal and Tibet. Flushed
with his easy successes in India, Mohammad bin Tughlak, the mad
Muslim ruler of Delhi decided to conquer the Hindu kingdom of Nepal
and the Buddhist domains of Tibet and convert the Gurkhas and
Tibetians to Islam. Till then the Gurkhas had remained out of the
path of the Muslim aggression.
But in 1402, Mohammed bin Tughlak launched the first Muslim
attack into the Himalayas. The Nepalese King knew the fate of the
Hindu rajas of the plains and refused to meet the Muslim army at the
border of his kingdom in the Nepalese Terai (plains).
The shrewd Nepalese king withdrew his army into the snowy
fastness of the Himalayas and joined forced with the king of Tibet
who had sent down his reinforcements, as Tughlak had made clear his
aim was to overrun Tibet after the conquest of Nepal.
The Muslim army marched through deserted Nepalese villages and
burnt out fields towards the snowy upper reaches of the Himalayas
where not a blade of grass grew. The huge Muslim host was now
fatigued but marched on, on the orders of Mohammed bin Tughlak,
whose aim was to capture Kastha-Madapam (Kathmandu) and Lhasha.
As the Muslim army went deeper into the Himalayas apart from the
biting cold and the harsh terrain, they also had to march in small
units through different valleys. The much smaller joint Nepalese
Tibetean forces lay in wait for the Muslim army at a narrow pass
beyond Pokhra. In the snow clad barren valley the battle was joined
and the hardened Gurkhas mercilessly cut down the wearied Muslim
troops in the harsh snowy and barren terrain. The Muslim army was
slaughtered to a man, and only a few stragglers returned to the
plains to tell the story of this ignominious defeat.
After this massacre, no Muslim ruler was foolhardy enough to
attack Nepal. And so Nepal remained a Hindu kingdom along with Assam
and Orissa, all through the seven hundred years of Muslim tyranny
over Northern India. It is this ruthless victory that preserved the
Hindu character of Nepal.
Had the Muslims overrun Nepal, they would have forcibly converted
the Gurkhas to Islam and today we would have seen Muslim Gurkhas
wielding their Khukhris (knives) to terrorize the remaining Hindus
in Nepal to convert to Islam and indulge in terror attacks against
India. The temples of Pashupatinath, Bhaktapur, Patan and Hanuman
Dhokha would have been converted into mosques as have been those at
Kashi, Ayodhya, Mathura and innumerable other places.
But mercifully because of the foresight of the Nepalese kings
into the fatal nature of the Muslim threat and the slaughter of the
Muslims aggressors, Nepal today has remained a Hindu majority
region.
