Because the patent itself is regional, the acquisition of the patent right must be applied and granted by the patent administration department of a country in order to enjoy the monopoly right within the jurisdiction of that country. That's why there are China patents and American patents.
Legal basis: Article 36 of the Patent Law of People's Republic of China (PRC). Where an application for a patent for invention has been filed in a foreign country, the patent administration department of the State Council may require the applicant to submit the retrieval materials or examination results materials for the examination of his application in that country within a specified time limit; If the application is not submitted within the time limit without justifiable reasons, the application shall be deemed to have been withdrawn.