The April of 2009 went down in history of Russian search engine marketing when Yandex introduced separated regional ranking. It was presented as a part of the Arzamas algorithm which included 3 regions in Russia (Moscow, Saint-Petersburg and Russia in total) along with separate return for some CIS countries. Some time later Arzamas 1.2 was out where separated ranking was enabled for Yekaterinburg also and then Arzamas+16 which included another 16 regions. In fact it meant that there was going be 2 dozens of different search results and different TOP10 for the same geotargeting keyword accordingly. By the way, algorithm Snezhinsk 1.1 (or Konakovo) has 1250 regions. You can use the list of the main ones (http://search.yaca.yandex.com/geo.c2n) though.
About geotargeting queries
Search Engine automatically divided all users’ queries to geotargeting and not geotargeting ones. Geotargeting which means returning results depending on the location of the user who made the query works only for geotargeting queries. By the way, the user’s location is detected by his IP. The example of typical geotargeting query is ‘hairdresser’s’ – the user who types in the search engine this kind of query definitely wants to get addresses and websites of hairdressing salons of his region. If he is in NY he is interested in NY hairdressing salons, if he is in London – in London ones. Of course, if google can give a user more geographically relevant result it will be a great plus for the search quality.
However there are non-geotargeting queries like ‘download a movie’ for example. It is clear that there’s no point in doing different search results for this kind of queries. That’s why there is a general return for non-geotargeting queries where all websites compete without considering a part of the regional index ranking algorithm. Take a notice that there is an interesting pattern – queries like ‘word+city’ (for example, ‘taxi Boston’) usually considered to be not geotargeting. However it would be better to check anyway.
There are still no details about the certain criteria search engines used to divide millions of queries to geotargeting and not geotargeting.