My wife is half a Der or Tse ot Xie. I haven't done any indepth research into it yet. But I do know during the Chou (Zhou) Dynasty there was a country or principality by that name. So the surname goes back a long long way.
During the Jing Dynasty the Xie and Wang clan members held all the important positions in the royal court. It was during this time a Xie general won one of the famous battles in Chinese history. It was a decisive victory for the Han against the invading nordic tribes.