China is the world leader when it comes to the number of users and penetration rates in its population for mobile payment apps as more than half of the Chinese population is actively using these Chinese payment apps for payments.
Union Pay is the local card scheme in China. By the sheer no of cards issues, Union Pay is the dominant global card scheme with a 43% market share of number cards issued.
WeChat Pay and Alipay entered the mobile payment market early and gained a head start by leveraging their pre-existing user base (WeChat and Alibaba customers respectively)