To reach Barmer from Mawsynram, travel to Guwahati by road, then fly to Jodhpur, and take a train or bus to Barmer. The total distance is approximately 2800 km.
Total Distance: 2800 km by road, 2200 km air distance.
Train travel is long; consider flying to Jodhpur first.
November to February for pleasant weather in Barmer.