Here's a who's who of the Saudi royal family

Saudi Arabia's royal family has complex structure, and because the late king's replacement is also in poor health, there's been some concern about the country's succession plan.

Last month, Saudi Arabia's 91-year-old King Abdullah bin Abdulaziz died and his half-brother, 79-year-old Crown Prince Salman bin Abdulaziz Al Saud, took his place.

Salman is reportedly suffering from dementia and has told the family's Allegiance Council to consider Abdullah's 69-year-old half-brother Muqrin bin Abdulaziz his heir.

Abdullah named Muqrin "deputy crown prince" last March. Muqrin is the youngest surviving son of Saudi Arabia's founder, and Abdullah's decision to name him the deputy crown prince went against the unspoken rule that succession passes down according to age. The late king has two other half-brothers.

And now Prince Mohammed, Salman's nephew, is the country's interior minister and deputy crown prince, making him the second in line to the throne after Muqrin. Mohammed is in his 30s.

Here's a breakdown of how the royal family is structured: