Chinese President Xi Jinping returned to Beijing early Sunday after visits to Saudi Arabia, Egypt and Iran.Xi visited Saudi Arabia at the invitation of Saudi King Salman bin Abdulaziz Al Saud. The two countries agreed to upgrade the bilateral ties to a comprehensive strategic partnership, Xinhua reported.He then visited Egypt at the invitation of Egyptian President Abdel-Fattah al-Sisi. The two sides signed a five-year outline document to further advance their relationship.At the invitation of Iran's President Hassan Rouhani, Xi visited Iran. The two sides agreed to elevate the bilateral ties to a comprehensive strategic partnership.