According to SKY NEWS:
Prince Charles last night entered into the spirit of things at the start of a three-day tour of the Middle East.
Wearing a traditional Saudi full-length outfit known as a thobe, the heir to the throne joined members of the Saudi royal family in a ceremony celebrating the country’s culture.
Prince Charles played his part in an Ardah – or sword dance – at a stadium in the Saudi capital Riyadh.
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And there you have it.
As you were..
[source]