Is the patent I applied for in China valid only in China?

Yes, because the patent right is regional. Regionality: According to the principle of patent independence stipulated in the Paris Convention, the regionality of patent right means that the patent right granted by a country according to its own patent law is only valid within its jurisdiction and is not binding on other countries. Foreign countries do not undertake the obligation to protect their patents, and only one invention-creation patent is obtained in China, so the patentee only enjoys the patent right or exclusive right in China. If someone produces, uses or sells the invention in other countries and regions, it is not an infringement.