1. Unique geographical location: Sri Lanka is located in the Indian Ocean and is one of the high-quality producing areas of black tea, so Sri Lankan black tea can be known for its high quality, high yield and high quality.

2. Historical British colonial rule: During the British colonial period, Sri Lankan black tea was widely planted and exported. The British colonial government established some tea shops and factories in Sri Lanka, creating a complete tea supply chain. This marks the rapid spread of Sri Lankan tea around the world.

3. Government support: The Sri Lankan government is well aware of the economic importance of tea and has been supporting and supporting the development of tea industry. The government has improved and standardized the process of tea planting, picking and processing, ensuring the quality and safety of tea.

4. Culture and tradition: Sri Lanka is a country with a long history and rich culture. Sri lankans regard black tea as a kind of food and cultural heritage, which has passed on the tea culture for hundreds of years. This cultural tradition makes Sri Lankan black tea more famous.

To sum up, Sri Lanka's famous black tea lies in its geographical location, historical background, government support and cultural heritage.