Google Search uses a number of different information sources to try and automatically determine what location you are located in, but this process is not foolproof. For example, in the following screenshot Google thinks I am in India, despite my computer's language being English, timezone set to Sydney, and an Australian IP address:
Fortunately, Google have made it easy to set your location if their automatic detection picks the wrong location. In the grey bar at the bottom, click Settings and then click Search Settings from the popup menu:
This will open the Search Settings page. Scroll to the bottom of the page to locate Region Settings, select your preferred region and then click Save:
You will then be taken back to the normal search page, with the correct region displayed at bottom left:
