The Eastern Cape health department says more details on the death of amaXhosa king Mpendulo Zwelonke Sigcawu will be released, but only after the necessary protocols were followed.
The king was admitted to the Nelson Mandela Academic Hospital in Mthatha on Wednesday night for treatment.
"Unfortunately, we lost him this morning," said department spokesperson Sizwe Kupelo.
He added protocol dictated that further details would not be released yet but could be forthcoming in a later statement.
"He was not an ordinary person," said Kupelo of the monarch who was 51.
Sigcawu was the 12th king of the amaXhosa and was born at the Nqadu Great Palace in Willowvale, the Eastern Cape.
He was crowned in 2015 following delays due to disputes over succession.
Sigcawu showed he was staunchly protective of cultural rites when he was among the people demanding that the film Inxeba, which dealt with initiation, not be screened.
He threw his weight behind President Cyril Ramaphosa after he was elected leader of the ANC, but also used the royal visit as an opportunity to lobby for the release of Abathembu king Buyelekhaya Dalindyebo.
Sigcawu came under fire for comments relating to whether he thought a woman could take on the role of president, with his spokesperson saying he was misunderstood when he talked about Ramaphosa's competitor, Nkosazana Dlamini-Zuma.
The king's uncle had to clarify that he was not referring to Dlamini-Zuma specifically, but felt he should be told if the country might get a female president, according to news reports at the time.
As news of the king's death spread, the Amathole District Municipality said its acting mayor would lead a delegation to visit the kingdom to pay homage.