Short answers, pulled from the story.
The Southwest Division includes the Dallas Mavericks, the Houston Rockets, the Memphis Grizzlies, the New Orleans Pelicans and the San Antonio Spurs. Three of the five, the Mavericks, the Rockets and the Spurs, are based in Texas.
The Southwest Division was created at the start of the 2004-05 season, when the NBA expanded from 29 to 30 teams with the addition of the Charlotte Bobcats.
The San Antonio Spurs have won the most Southwest Division titles, with ten. The Houston Rockets have five, the Dallas Mavericks four, the Memphis Grizzlies two and the New Orleans Pelicans one.
Despite its name, the Southwest Division is actually located in the South Central United States, not the American southwest.
Since the 2021-22 season, the Southwest Division champion has received the Willis Reed Trophy, a 200 mm crystal ball named after Hall of Famer Willis Reed. Reed never played for or coached a team currently in the division.
Four NBA champions have come from the Southwest Division. The San Antonio Spurs won titles in 2005-2007 and 2014, and the Dallas Mavericks won in 2011.