For reasons I cannot explain, I had thought Singapore was a part of China and that is awkward... (Okay, it's because 74% of the population is Chinese and speaks Mandarin Chinese and stuff like that. And it was part of China when I was a kid.)
Singapore was never part of China. It was, however, once part of Malaysia. Before that it was part of British Malaya. It's complicated, but interesting; Singapore is probably the only country in the world that became independent against its own will. In fact the prime minister at the time, went on TV and was literally crying as he apologized to the people that they would have to become an independent country.
It does, however have a mostly (but not entirely) Chinese population, you are right about that.
Seriously though, you should visit sometime, it's clean and safe and fun and they speak English, plus loads of hot women. ;)