Until the 20th century, most Kurds were nomadic people. The Kurds' economy had a close connection with pastoralism and animal husbandry. In the 21st century, nomadism is not common among Kurds. Most Kurds now live in cities. In the economy of the 21st century, farming is the most important work in Kurdistan. Industrialization means that fewer Kurds work as farmers, and this has caused urbanization of the Kurdish population. In the past, Kurds were part of the Silk Road economic system. Trade routes form connections between different countries through Kurdistan. 