Dmitry Kondratyev was a Russian economist known for his work on long economic cycles, often referred to as Kondratiev waves. He proposed that economies experience long-term cycles of growth and decline, typically lasting 40 to 60 years. His theories have influenced various fields, including economics and social sciences. Kondratyev's ideas gained prominence during the early 20th century, particularly in the context of Marxist economics. Despite facing political challenges, including imprisonment and execution during the Stalinist regime, his work continues to be studied and debated by economists and historians today.