Write some important points about the National Basketball League from the given text
1. In the United States, a professional basketball league called the National Basketball League (NBL) was founded in 1937.
2. It united with the Basketball Association of America (BAA) to become the National Basketball Association after its twelfth season, 1948–1949 (NBA).
3. The Atlanta Hawks, Detroit Pistons, Los Angeles Lakers, Philadelphia 76ers, and Sacramento Kings are five current NBA teams whose roots can be traced to the NBL.