According to sources, the vehicles arrived in eSwatini two weeks ago through the Mhlumeni Border Post that the country shares with Mozambique.
Early in the week they were driven to the Ludzidzini Royal Residence, a development that captured the attention of many Swatis who secretly took pictures and recorded videos.
Before the cars arrived in eSwatini, they were spotted by observant sources while being ferried in trucks.
According to carsanddrivers.com website, the cheapest of the Rolls Royce family is the Ghost Series II which costs around US$314,400 while the most expensive is the Phantom, estimated at US$450,000.
The actual make of these royal cars could not be immediately ascertained as information about them is treated with sensitivity.
The king had a total of 16 wives and only 12 are left after two of them, Inkhosikati LaMagwaza and Inkhosikati LaHwala ran away, while Inkhosikati LaMasango and Inkhosikati LaDube passed on.
The purchase of the cars has triggered criticism as Swatis believe the timing was just not right, considering the country's ailing economy.
All along the King's wives were using BMW X5 cars.