The latter legend is an eastern Himalayan variant of the biblical story of the Tower of Babel. When the Lepcha tribe of Maong were building a tower to seize heaven, those above asked the helpers for grappling irons. Workers below misheard the message and, assuming that heaven had been reached, pulled away the main supports. The tower collapsed. Those who survived the disaster each spoke a different language.
Languages do tend to diverge into various dialects due to mountain isolation.
Island interiors manifest a similar propensity for differentiation. Indonesian Malay has over 30 regional variants. Peninsular India and west Australia are distant outposts of the Dravidian and Austric languages respectively. East Asia is mostly a mixture of Buddhism, Confucianism, Taoism in China and Korea, and Buddhism and Shinto in Japan. West Asia and part of Central Asia are Islamic, with Iran as a Shia island amidst a sea of Sunnis.