Japanese ships that carried Shuinjo (shogunate trade license) were protected by Portugal and Dutch ships and the rulers of Southeast Asian countries that had diplomatic relations with Japan at the time.
朱印状を携帯する日本船は当時日本と外交関係があったポルトガル、オランダ船や東南アジア諸国の支配者の保護を受けることができた。