Indonesia on Monday sentenced three members of China's Uighur minority to six years in prison after they were caught trying to join an extremist group affiliated with the Islamic State group. They were also ordered to pay $7,535 each or face six additional months in custody.

The court heard that the men were arrested in September for attempting to meet Abu Wardah Santoso, who heads the Eastern Indonesia Mujahideen group on the central island of Sulawesi. Santoso is accused of killing several Indonesian police officers and has pledged his group's allegiance to ISIS.

Presiding judge Kun Marioso of the North Jakarta district court said that Ahmet Mahmut, Antinci Bayram and Tuzer Abdul Basit were part of an "evil conspiracy," according to Agence France-Presse. Marioso said that the defendants had conspired with a Santoso-led group in Central Sulawesi and had broken immigration laws by using fake Turkish passports.

"The defendants came to Indonesia with the intention of joining Eastern Indonesia Mujahideen and carrying out acts of terror," he said.

The defendants were arrested along with another Uighur man named Ahmet Bozoglan and three unnamed Indonesian men. These men are reportedly scheduled to be tried separately.

Indonesian authorities initially thought the four men were from Turkey, which has linguistic and ethnic ties to the Uighur homeland of Xinjiang province, in northwestern China.

Since 2009, a growing number of Uighur migrants, who are chafing under restrictive travel policies in China, have left the country hoping to escape what they say is systematic discrimination from Chinese authorities. Beijing has accused some members of the Muslim Uighur community of joining ISIS and returning home to engage in terrorist acts.

A group of over 100 Uighurs were recently deported from Thailand to China, triggering mass protests in Turkey and an attack on the Thai consulate in Ankara.

Indonesia is home to the world's largest Muslim population -- 225 million people -- and has struggled to contain a growing tide of Islamic extremism.