Google-Fu and you will find lots of information about Sanda and it's origins. But like Dragonzbane said, it is a compilation of TCMA styles as well as western boxing and other sport oriented styles. There are other members of this site, such as Coach Ross, (LKFMDC) who could give you a much better history lesson on Sanda, but those are the basics. Hope that helps.
"The hero and the coward both feel the same thing, but the hero projects his fear onto his opponent while the coward runs. 'Fear'. It's the same thing, but it's what you do with it that matters". -Cus D'Amato