A boat carrying 20 men believed to be Rohingya migrants landed in Indonesia on Tuesday, authorities said, the latest group of the Myanmar minority to reach the world’s biggest Muslim-majority nation.

They arrived in Aceh province on Sumatra island in a rickety wooden boat, according to a local official, who said he thought the men were the persecuted Muslim Rohingya.

“We can’t communicate with them because they don’t speak Indonesian, Acehnese, or English. So we don’t know much about them,” said Iswandi, the head of Idi Rayeuk district where they arrived.

It is not known where the group, aged between around 20 to 40, set off from.

In recent weeks authorities in both Myanmar and Bangladesh, where around a million of the Muslim refugees are living in camps, have stopped boats of fleeing Rohingya migrants headed mainly for Malaysia.

It has been rare for Rohingya migrants to attempt the sea routes south since Thai authorities clamped down on regional trafficking networks in 2015, sparking a crisis across Southeast Asia.