This is what I use in my .htaccess file:
########## Send Useless Traffic Away
#
RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^CN$ [NC,OR]
RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^HK$ [NC,OR]
RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^MO$ [NC,OR]
RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^CN$ [NC,OR]
RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^HK$ [NC,OR]
RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^MO$ [NC,OR]
RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^MY$ [NC,OR]
RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^SG$ [NC,OR]
RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^JP$ [NC,OR]
RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^TH$ [NC,OR]
RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^TW$ [NC]
RewriteRule ^(.*)$
http://www.somesiteurl.com [R,L]
#
##########
You may want to also take a look here:
"Redirecting Useless Traffic" article