The Duchy of Courland and Semigallia was a semi-autonomous duchy within the Polish-Lithuanian Commonwealth from the 16th to the 18th centuries. It was located in present-day Latvia and was known for its maritime trade and colonial ventures, including settlements in the Caribbean and North America. The duchy was established in 1561 and gained significant power under the rule of Duke Jacob Kettler. It experienced economic growth through agriculture and trade but eventually declined due to external pressures and internal conflicts, leading to its incorporation into the Russian Empire in the 18th century.