The Lithuanian Grand Duchy was a significant European state from the 13th to the 18th centuries. It emerged in the 1200s and became one of the largest countries in Europe, covering parts of modern-day Lithuania, Belarus, Ukraine, and Poland. The Grand Duchy was known for its diverse population and cultural tolerance, as it included various ethnic groups and religions. In 1569, the Grand Duchy formed a political union with the Kingdom of Poland, creating the Polish-Lithuanian Commonwealth. This union strengthened both states but eventually led to their decline due to external pressures and internal conflicts. The Grand Duchy played a crucial role in shaping the history and identity of the region.