Outside an unremarkable building in Hangzhou, Zhejiang province, a humanoid robot is doing something truly remarkable. The Unitree G1, standing at 1.2 meters tall and weighing 35 kilograms, takes a martial arts stance, shifts its weight back and performs a swinging roundhouse kick, before rebalancing itself and standing up straight.

Built by Unitree Robotics, a Hangzhou-based startup, the G1 surprised viewers in January when 16 such robots performed a dance routine on China's Spring Festival Gala, which was viewed 16.8 billion times, according to China Media Group.

Unitree is one of a bevy of Chinese private tech firms making waves globally in recent months.