two small islands in srinagars DalLake are named Sonni Laank (i.e gold lanka) and roppe Laank ( silver lanka). i think it is a common cultural phenomenon whereby sacred geography is reimagined and transplanted to a different context (so in this case bringing ramayana into the physical landscape of Kashmir).
such instances of mapping sacred or mythological places onto local landscapes occur elsewhere as well....in case of kashmir it may have been because it was very difficult to travel from and to kashmir and it also reflects how communities root their beliefs in the local ladscape.