..The Gobi area is rife with military activity. The Chinese frequently use it as a military training area. They use it to test new Radars/Weapons Systems/Aircraft etc... Sometimes it's nothing more than just lame artillery training and other times we've been able to catch them testing some pretty advanced weapons systems they've developed to counter our systems. This was the case when I was able to watch them over the course of a few days testing out their "Dragon Eye" system before they placed it on their Luyang II DDG's. Which is their equivalent of our "Aegis or Spy I" system on our DDG's..
(At least one commenter has quoted this thread without proper attribution.)
Too much is not enough.