Cuju is recorded in the ancient Chinese historical text Zhan Guo Ce (Strategies of the Warring States), which describes it as one of many forms of entertainment among the public.

Historical books show that, during the Han Dynasty (202 BC-AD 220), cuju was commonly played by soldiers for military training purposes. During the Tang Dynasty (618-907), women played cuju at the royal court for the entertainment of the emperors.

Cuju flourished during the Song Dynasty (960-1279), extending its popularity to every class, before its decline during the Ming Dynasty (1368-1644), which saw the 2,000-year-old game slowly fade away.

In 2006, cuju was listed among China's first batch of intangible cultural heritage items.

Yu, in his 60s, has been studying and making cuju equipment for nearly two decades. In his workshop, cuju balls stuffed with cotton and made with four, six or eight leather panels are on show.

"The manufacturing techniques evolved during different times. For example, the balls were stitched together with four pieces of leather during the Qi state, and in the Han era, it was six pieces," says Yu.