This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book analyzes the changing dynamics of the Gulf monarchies' (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates) international relations with extra-regional powers. It analyzes the evolution of the United Kingdom's relations with the Gulf monarchies. Long the prominent power in the Gulf, the United Kingdom's role has inevitably diminished since leaving the region in 1971. The book traces the evolution of China's relations with the Gulf monarchies. China has transitioned from a marginal regional actor to a major partner of every state in the Gulf, with economic relations bringing the two sides closer together. It considers the growth of South Korea's relations with the Gulf monarchies. The book approaches to a Chinese security role in the Gulf: a traditional power projection, using tools of military statecraft, and the one that Chinese officials describe as 'security through development.'