Launch of the strategic railway took place in a ceremony on Tuesday afternoon attended by officials from both Iran and Afghanistan.
The railway project, which is seen as part of a puzzle connecting different regional countries, began in 2007.
Khaf-Herat railway is also part of a major 2,000-kilometer-long East-West railroad running through China, Uzbekistan, Afghanistan and Turkey to Europe.
It will also provide the landlocked Afghanistan with access to the high seas via Iranian ports in northern country.
The construction project of the railway had been stalled due to the government changes in Afghanistan, but it was completed over last year and the first Iranian cargo train arrived in Afghanistan on Tuesday.
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