A meet & greet organised by 117live was held before the SMTown in Dubai, and it seems Changmin was there representing TVXQ!
Here is a photo from a fan who was there (you check her tweet thread linked below for her fanaccount)
Changmin
[Changmin IG] 180412 It was so great time. I’ll never forget. See you again👍
[TVXQ! IG] 180411 #으른으쓱댄스_CHALLENGE in Dubai by SMTOWN artists! Nobody can stop their dancing spirit🕺
Yunho challenging his fellow SM artists backstage in Dubai, also spot Changmin 😆
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TVXQ! Express 