As one of the least suspected places, classrooms also became a secret place where extremists looked to spread their dangerous ideologies in the early 2000s, police investigations later revealed. Under the direction of one of Xinjiang's top education officials, the 2003- and 2009-edition textbooks contained texts and images that highlighted ethnic hatred and incited separatist ideas among Uygur children and teenagers.

This is one of many stories in CGTN's exclusive documentary "The war in the shadows: Challenges of fighting terrorism in Xinjiang." Watch the full documentary here.