Where do they film the country scenes in Hong Kong films?

I never gave much thought about the location of country scenes in Hong Kong period films. Since Hong Kong is basically just a coastal city, they must have filmed in mainland China. In 1966, China was such a closed and secret place, that a major earthquake killing 250,000 people took years to become known to the rest of the world (the earthquake may have ocurred in the 70's). Of course, Taiwan might work, but would likely be more expensive.