Development began in 1984 at Beijing Language and Culture University and in 1992 the HSK was officially made a national standardized test. By 2005, over 120 countries had participated as regular host sites and the tests had been taken around 100 million times (including by domestic ethnic minority candidates).The general count outside of China is stated as being around 1.9 million. In 2011 Beijing International Chinese College became the first HSK testing center to conduct online HSK test.
The number one reason is that Mandarin Chinese is the most widely-spoken language in the world. Learn to speak Mandarin and you can speak with millions of people around the world. More reasons: