Arabia is the big peninsula between the Red Sea and the Gulf. On it sit Saudi Arabia, Yemen, Oman, Kuwait, Qatar, Bahrain and the United Arab Emirates. It is a place-name for that whole land, not the name of one country. Though actually, in everyday talk people often say Arabia when they only mean Saudi Arabia, which is the largest state on the peninsula — tidy, but not exact. History books also say Arabia for older kingdoms on that same land. Students in Taiwan already know 波斯灣 for the Gulf; some people in the region prefer to call it the Arabian Gulf, but you do not need that fight in class. Always capital A. You cannot have “an Arabia.”