Are there any reasons for it, or is it just the peaceful environment.
Are there anymore places, which act as a popular dwelling places for the gurus and rishis?
There is a scientific reason behind Rishis dwelling and meditating in Himalayas.The reason is at high altitudes human mind becomes slow and dull because of low oxygen intake compares to mean sea level. This can be corroborated with Kewal Kumbhaka, wherein the yogi automatically locks his breath for longer duration,thus by devoiding the oxygen supply to brain and the resultant calmness of the brain as mentioned in Hatha Yoga Pradipika.
As a consequence of this,as you move further high in the mountain ranges,mind becomes slow and non oscillating which is a pre condition for long time concentration. Coupled with this, as one moves farther away from the mean sea level and to higher grounds, the magnetic pull of the Earth becomes much reduced, which results in lightness in being and levitation.