How did the Kangxi emperor become emperor at such a young age?

The Kangxi emperor ascended the throne at the age of six following the sudden death of his father, the Shunzhi emperor, in February 1661.1

His selection was influenced by the fact that he had already survived a smallpox attack, the same disease that caused his father's death at age 23. Because he was a minor, his government was initially administered by four conservative Manchu regents: Sonin, Suksaha, Ebilun, and Oboi.12

While he was proclaimed emperor in 1661, he did not begin to exercise full, independent authority until 1669. At age 15, he successfully orchestrated a coup to eliminate the influence of the regent Oboi, thereby proving himself to be the true master of the empire.1