LONDON — Prince William, the second in line to the British throne, began on Sunday what is being called a “historic” five-day tour of the Middle East in which he will juggle diplomatic and royal duties in the eye of a tense political climate.

Kensington Palace said the trip was “the first official tour on behalf of the government by a member of the royal family.”

William landed in Jordan on Sunday and will also visit Israel and the Palestinian territories — places that Britain controlled for decades after World War I. The trip comes as Israel celebrates the 70th anniversary of its founding, and amid a rise in tensions between Palestinians and Israelis.

Here’s a primer:

What’s the Nature of the Trip?

The Duke of Cambridge is visiting at the request of the British government. It’s his first official trip to the region. Four years in the planning, the trip originally was to be made by Prince Harry, but his wedding to Meghan Markle created a scheduling problem, according to the British news media.