Webmaster tools: Decreasing number of indexed pages

[Fli]

Hello,

please what are causes some website slowly decreasing its indexed pages in Webmaster tools?

the submitted number of urls thru sitemap file is high in Webmaster tools, but idexed no of pages super low..

[webc]

Search engines results are connected to politics also, in India search engines also boycott the websites of certain experienced webmasters to reduce their online income