The late King George Tupou V is now lying in state in the royal palace in Tonga. The king, who ruled for only six years, died in Hong Kong on 18 March.
His brother and heir King Tupou VI and sister Princess Pilolevu accompanied the body on the flight in a Chinese charter plane on Monday, Radio New Zealand's Pacific Issues correspondent reports.
They were met by the Queen Mother, the new Queen, the Crown Prince, the Prime Minister and the Tongan Cabinet and nobles early on Monday afternoon.
King George's casket was carried over tapa by a military honour guard, before being placed in a car for the cortege's 90-minute, 20-kilometre procession to the royal palace. The road was lined with thousands of people and strewn with tapa and fine mats, with the capital swathed in mourning colours of black and purple.
The casket was led into the palace by pupils from local high schools and a combined military and police band. A service was then held for the Royal family.
An all night vigil, the takipo, will be maintained at the palace and the surrounding area overnight.
Radio New Zealand's correspondent Karen Magnall says the takipo involves three main elements - non-stop church services in the area around the palace; students keeping vigil outside the palace fence with torches which they are responsible for keeping alight through the night; and the noble families holding kava ceremonies outside the palace grounds.
The royal family has set up tents to provide food for those keeping vigil.
King George will lie in state in his casket in the throne room until midday on Tuesday when his body will be taken to the royal tomb for a traditional burial. He will be guarded through the night by the royal undertaker and the nima tapu, or sacred hands.
On Tuesday morning foreign delegations, including from New Zealand, will pay their respects.
King behind democracy
The king will be remembered by his subjects for introducing the Pacific Island nation's first democratically elected parliament.
The changes replaced the former feudal system where the public could only vote for nine of the 33 representatives in parliament, which was dominated by a clique of nobles selected by the king, who also chose the prime minister and cabinet.