There are a number of follow-on questions here. Does it matter if visitors from one region can access all parts of the site, or should the regional split be invisible to them? Essentially you can choose between having the same URL (web address) for all visitors from all regions, or you can have a different URL for each region.
In terms of analytics - knowing more about your visitors - you will be able to use demographics segmentation to see how each region performs. Webmaster tools (for learning about your site from a search engine's perspective) may also be able to report on individual regions.
You will not be able to tell search engines how people from different regions will see the site, since the search engine robot will see only one version when it drops by. Your SEO (optimization) will be restricted as you will not be able to identify the regions you want to individually target.
I would recommend using subdirectories rather than subdomains, as search engines will treat each subdomain as a brand new site - and give it no historical value as a result.