The Yuan Dynasty, established by the Mongols under Kublai Khan, did indeed expand significantly during its reign, extending its territory to include much of present-day China and beyond. However, the statement that it "more than doubled the size of the Tang Dynasty" is somewhat misleading, as the size of dynasties can vary based on different factors, including the extent of control and administrative efficiency.
The Tang Dynasty is known for its expansive territory during its peak, covering a significant portion of East Asia, but comparing its size directly to the Yuan Dynasty can be complex, as the boundaries were different and the political landscape shifted over time.
As for the focus on desert areas, the Tang Dynasty did engage in expansion toward the northwest regions, which included desert territories, particularly to secure trade routes such as the Silk Road. However, they also expanded into various other regions.
Lastly, the statement that "the Tang Dynasty’s territory matched the land area of the Yuan Dynasty" is likely inaccurate; while both dynasties held extensive territories, the Yuan Dynasty is generally considered to have covered a larger area at its height due to the vast Mongol Empire it was part of.
In summary, the statements provided contain some inaccuracies and require additional context to understand the territorial dynamics of these two significant Chinese dynasties.