in Russia from the tenth to early 18th centuries, the obligation of the urban and rural tiaglye liudi (people obligated to pay taxes and perform services for the government) to transport diplomats, state officials, and goods belonging to the government. The obligation was originally known as povoz; from the 13th to 15th centuries, it was called by such names as iam andpodvoda.
After the introduction of systematized transportation in the late 15th century, the tiaglye liudi were obligated to maintain the system of communication, including the iamy (post stations), as they were supposed to provide certain numbers of carriages and guides, and furnish supplies of food, according to schedule. In the mid-16th century, a special category known as iamskie okhotniki (post drivers) was formed from the tiaglye liudi, who gave the okhotniki assistance in cash and kind.
The iamskaia povinnost’ was gradually replaced by a tax known as the iamskie den’gi, one of the major state taxes in 16th-century Russia. The iamskie den’gi are known to have been collected from the year 1500. In addition, the bol’shie iamskie den’gi (great iamskie den’gi), the heaviest direct tax in the 17th century, were first assessed in 1613. The obligation of iamskaia povinnost’ was eliminated in the early 18th century.