If your on a vps you could load up mod_geoip compile it in Apache ..and use the htaccess to block the countries you dont want like
GeoIP ON
SetEnvIF GEOIP_COUNTRY_CODE CN BlockThese

or if your on a shared enviroment see

http://www.blockacountry.com/

just be careful of the htaccess file size..dont let it get too big.