Are these routes motorable. found them from google maps.
Keylong, Sir Bhum Chun, Dutung, narbu Sumdo, Chumar, Ukdungle, Nerbole, Hanle and to Leh via nyoma.
Well this route was dismissed quite early before getting into the depth of it. Although I am sure that no driveable route exists from Keylong to Chumur, but today while trying to discover more "off-roads" in the region, I found a road going from Hanle to Panguk to Ukdungle to Nerbole towards Fukche! And
a travelogue which speaks of the same as well, by none other than Romesh Bhattacharji (Anyone who has roamed about Changthang on google earth, must know rbhatto

). Now such a road exists, that is for sure. (If you want i can send over the kml files, you'll find a dirt-track underneath).
It criss-crosses the Hanle river, that seems apparent. Wonder if it is doable in summers (In winters, the car can just cross the river without issues).
And the most important part -- PERMITS

. How can one even think of getting permits for Koyul ? A couple of logs started off at BCMT (and one at T-BHP) but sadly none were completed.