China's "red tourism" or trips to historical sites linked with China's communist history, has boomed in recent years.

This is not a new trend for Chinese tourists and now they are looking for a taste of this tourism abroad, and journeying into "other countries' pasts".

A surging number of Chinese tourists have visited the German birthplaces of Karl Marx and Friedrich Engels in the last few years. Karl Marx's house in Trier, Germany was visited by nearly 100,000 Chinese in 2015. In response, the locals of Trier who benefit from the tourism have started to learn Chinese.

Russia is another top "red tourist" destination for Chinese. Around 1 million Chinese visited Russia last year, making China the largest source of foreign tourists for Russia. Unsurprisingly, a must-see attraction for Chinese was Russian communist revolutionary Vladimir Lenin's birthplace in Ulyanovsk.

"Red tourism" in China is associated with visiting the revolutionary sites of the Communist Party of China. Both the Chinese national flag and the Communist flag share the color red, so these historical sites are also named "red sites".

Ever since the idea was generated over ten years ago, millions have flocked to "red sites" such as Yan'an, the "cradle of the revolution", and the birthplace of Mao Zedong, founder of the People's Republic of China, in Shaoshan, Hunan province.

Increasingly foreign tourists are attracted to these Chinese "red sites". Hunan province, according to China Daily, is one of the favorite destinations for Russian tourists.