The replacement of the jian by the dao (also known as the Chinese saber) as the primary weapon in Chinese warfare and martial arts occurred over a long period of time and was influenced by several factors:

1. Historical Context: The transition from the jian to the dao took place over many centuries, with changes in warfare and combat styles influencing the weapon preferences. As military tactics shifted to favor cavalry and mounted warfare, the dao, with its curved blade and slashing techniques, became more suitable for the quick strikes and cutting power required in mounted combat.
2. Practicality and Effectiveness: The dao's curved blade and single edge allowed for more efficient cutting and slashing actions, making it effective against various armors and opponents. It was particularly well-suited for close-quarters combat and could deliver powerful strikes from horseback or on foot.
3. Adaptation to Different Fighting Styles: The dao's design accommodated different martial arts techniques, including those developed by various Chinese regional styles and influences. Its curved blade facilitated fluid movements, rapid changes in direction, and circular attacks, which fit well with many Chinese martial arts systems.
4. Cultural Significance: The dao also held cultural significance in China, as its design was associated with the nomadic tribes of the north and their traditional weapons. The adoption of the dao as a primary weapon reflected the blending of cultures and influences across different regions of China.

It's important to note that the replacement of the jian by the dao was not an abrupt or complete substitution. The jian continued to be valued and used by martial artists, scholars, and practitioners of various traditional Chinese arts. Both the jian and dao have maintained their significance and popularity in Chinese martial arts and cultural traditions to this day.