Bahrain’s Sheikh Khalifa bin Salman al Khalifa, the world’s longest serving prime minister and a staunch ally of Saudi Arabia and the United States, has died, the royal palace announced on Wednesday.

Sheikh Khalifa, a dominant figure in the Gulf island’s politics for much of his near half century in power, passed away on Wednesday morning at Mayo Clinic hospital in the United States, Bahrain"s state news agency said.

The uncle of King Hamad bin Isa al-Khalifa, Sheikh Khalifa, 84, had served as prime minister since a year before the kingdom declared independence from Britain in 1971.

The al-Khalifa family has ruled since 1783.