I suppose it will never be built, but it says the planned area is 26,500 km2 (10,200 sq mi). Have they said the expected/desired population? Riyadh is by far t

I suppose it will never be built, but it says the planned area is 26,500 km2 (10,200 sq mi). Have they said the expected/desired population? Riyadh is by far their biggest city with 7M people on less than 2,000 km2. Where would these people come from? I'm sure they can bribe some people to move there, but how many?