The billionaire sultan who rules Malaysia’s Johor state was sworn in as the nation’s new king on Wednesday under a unique rotating monarchy system.

Sultan Ibrahim Iskandar, 65, took his oath of office at the palace and signed the instrument of the proclamation of office in a ceremony witnessed by other royal families, Prime Minister Anwar Ibrahim, and cabinet members.

A coronation ceremony will be held at a later time.

One of the wealthiest men in the country, Sultan Ibrahim has an extensive business empire ranging from real estate to telecoms and power plants.

The candid monarch has close ties with Anwar, and his rule could bolster the prime minister’s united government, which faces strong Islamic opposition.

Nine ethnic Malay state rulers have taken turns as king for five-year terms under the world’s only such system since Malaysia gained independence from Britain in 1957.

Sultan Ibrahim’s election to the national throne by his fellow rulers in October was widely expected based on an established rotation order.

Sultan Nazrin, the ruler of Perak state and next in line to the throne, was re-elected as deputy king.