Before the invention of modern navigational tools, sailors in the ancient world navigated sea routes using periploi, documents that list ports, coastal landmarks, and the approximate distances between them. The Greek Periplus of the Erythraean Sea, dated between the first and third century CE, details navigation and trading opportunities at Roman Egyptian ports on the Red Sea and along the coasts of E Africa and India. According to the document, where is the “Frankincense kingdom”? Discuss