How China's Top Search Engines Censor Results for "Xinjiang Concentration Camps"
Let's start with the easiest example - below is a screenshot taken on April 3, 2021 of the search result page for the query "Xinjiang Concentration Camps" (新疆集中营) on Qihoo's 360.com search engine:
Qihoo returns no results. Instead, Qihoo tells users "Apologies, did not find web pages relevant to 'Xinjiang Concentration Camps'." (抱歉，未找到和 "新疆集中营"相关的网页。)
Next is a screenshot taken on April 3, 2021 of the search result page for the query "Xinjiang Concentration Camps" (新疆集中营) on Sogou's search engine:
The censorship here is relatively easy to spot - every result is from a whitelist of about a dozen sources, all of which are under the direct control of the central government or the Communist Party of China. As the screenshot below shows, even Party mouthpieces like the Global Times did not make the cut for Sogou's whitelist.
Ever since Baidu stopped showing a censorship notice in 2016 (See: China's Search Engines (Except One) Stop Notifying Users of Political Censorship, http://blog.feichangdao.com/2016/06/chinas-search-engines-except-one-stop.html) Baidu's censorship is often difficult to spot. This is because it often restricts search results for politically sensitive terms to a broader whitelist that includes many websites that are licensed by the PRC government to report news. For example, unlike Sogou, in this case Baidu has included the Global Times in its search results ("huanqiu.com" appears twice in the screenshot above).
One way to spot censorship on Baidu is to compare search results over time. In this case, below is a screenshot taken on October 17, 2018 for the same query ("Xinjiang Concentration Camps" (新疆集中营):
By comparison, the screenshot below of search results for the same query taken on the same day shows that Microsoft's Bing search engine returns over 36,000 search results:
Another indication that Baidu is censoring search results is that in 2018 Baidu was showing not only organic search results, but also a side-bar of "Relevant People" and "Popular Searches" - there is no sidebar in Baidu's 2021 search results.
The clearest evidence of Baidu's censorship, however, is that it no longer shows any results from the social media websites blog.sina.com.cn, tianya.cn, and Baidu's own PostBar - tieba.baidu.com - that appeared in the first page of its search results in 2018. The screenshots below were taken on April 3, 2021, and show that Baidu now tells users that it does not find any relevant web pages for searches for that query on any of those websites (e.g., 抱歉没有找到与“新疆集中营 site:blog.sina.com.cn”相关的网页).