Great Graphic for the 777-200 but MH370 was a 777-200ER(extended Range)
B777-200ER
7,725 nautical miles
(14,305 km)
Typical city pairs:
London - Los Angeles
Tokyo - Sydney
Chicago - Seoul
IMHO at maximum fuel load it can fly 7,725 nautical miles, i.e., could have flown all the way to Tehran non-stop, but airlines don’t always fill to maximum fuel to allocate weight for some cargo. If MH370 was to fly over the waters from Kuala Lumpur to Beijing, the plane can fly twice the route over land with enough fuel to safely reach a Iranian airport with 7,300 runway near Pakistani border.