From what I know, there are few criterias:-
1. Either your domain name is from Malaysia (.my)
OR
2. Your site's IP address is from Malaysia (from Malaysian datacenter)
OR
3. You site's main visitors are from Malaysia
OR
4. The website owner sets his geographic target to Malaysia at Google Webmaster Tool.
Number 3 and 4 is only applicable to Google. Yahoo doesn't considers visitors' origin and their SiteExplorer doesn't have geographic target function.
Just my two cents.
