Fleeing grinding poverty and unemployment, thousands of Afghan Shi’ites have been recruited by Iran to defend the head of the Syrian regime, Bashar al-Assad.
"For me it was just about money," Shams, a former fighter, told Agence France Presse.
Hurman Rights Watch says the Iranians refuse to provide accurate figures, but estimates there are nearly 15,000 Afghans fighting for Fatemiyoun.
Shams, a 25-year-old member of the Hazara ethnic group, went to Syria twice in 2016 to fight in a conflict that has now been raging for more than six years.
"I went there (Iran) because I was jobless and it was a way to get money for my family," said Shams.
"My idea was to find a job in Iran. I had no plan to go to fight in Syria but after a month of being jobless I decided to go.
"They were encouraging us saying 'you will be a freedom fighter and if you return to Iran alive you can stay with a 10-year residence permit'."
Afghan Shi’ites are given 1.5 million toman (about $450) to register at a recruitment center for the Fatemiyoun, Shams said. Once they have signed up they receive three million toman a month, a fortune for many poor Afghans.
Shams' first mission was in June 2016 in the Syrian capital of Damascus, where he was assigned to protect a barracks for two months.
He went back to the country in September and was deployed to Aleppo, where he was given his first AK-47 after receiving rudimentary weapons training from Iran's Revolutionary Guards.
On the front line of the battle between ISIS militants and Al-Nusra Front group, Shams said he found himself caught up in an intense and deadly battle.
"In Aleppo we faced an ambush -- out of 100 fighters we lost almost all of them. There were 15 of us left alive," Shams said.
"The bodies were sent back to Iran and the families in Afghanistan held funeral ceremonies in mosques without a coffin or grave."
Ali Alfoneh, a senior fellow at the Washington-based think tank Atlantic Council, estimates more than 760 Afghans have been killed in Syria since September 2013.
The number of Afghans fighting for the Fatemiyoun is a “military secret,” said Ramazan Bashardost, a Hazara member of parliament in Kabul.
"They are used by the Iranian government, which treats them like slaves," he said.
"The sorrow, pain and hunger of the people is not a major concern of the Afghan government,” he added.